d link modem wiring diagram. Network based on xDsl modems

The router is used to connect several devices to the Internet, a computer, laptop and others, via wired or wireless technology and create a local network between these devices. At the same time, the router implements a barrier between the local network it created and the Internet. Basically, routers work using NAT - Network Address Translation. Sometimes providers provide routers along with the connection, the router can be inside a DSL modem or cable, or purchased separately. But, like any electronic device, routers can fail and many malfunctions can be fixed at home on your own. Consider some common router malfunctions and methods for their elimination, d link router repair.

Most often, the following reasons lead to router malfunctions:

  1. large voltage surges in the network,
  2. router overheating,
  3. router software failures (firmware failures),
  4. high-frequency interference of electromagnetic radiation during a thunderstorm (in this case, the wan port most often burns out if the provider does not put lightning protection on its cable),
  5. human factor.

If the router malfunctions, it can lose data packets, work on the Internet and local network is disrupted, the firmware is lost, the router can turn off, flash all the indicators.

Solving a problem associated with the inability to enter the router settings at its network address 192.168.0.1

If, after typing the network address of the router in the address bar, the router settings page does not open, then to eliminate this malfunction, you should perform the following operations:

  • First, check that you have set the network card settings to automatically obtain an IP address and a DNS address (a direct connection to the router is used).

  • If the network card settings are correct, then you need to use the Run command (press the Win + R key combination), then type - cmd and press enter. Now at the command line you need to enter ipconfig.

command line "ipconfig"

In the displayed settings, you need to see what value is opposite the inscription - Main Gateway. This address is used to enter the router settings. If the value of this address does not match the standard value, then the router may have been configured for a specific network with its own requirements. In this case, you need to reset this value to the factory settings. Sometimes in this field there may be no address value at all, and you also need to reset the router. To reset the router, you need to press and hold the Reset button on the router for a while. Usually five or ten seconds is enough. The button hole is narrow enough that you can use a ballpoint pen, needle, or paperclip to press it.

If resetting your router doesn't help, unplugging your ISP cable from your router may help. Pull out the provider cable from the router connector and configure the router without the cable connected. After that, you can reconnect the cable to the router.

Also check the firmware version installed in the router. Check the manufacturer's website for the latest firmware and update it if necessary. You can also check your network card drivers on your computer and reinstall them if necessary.

If the router settings are not saved

To troubleshoot a problem with not saving the router settings or if it is impossible to restore the settings from a separate file, you can try to carry out these operations by opening another browser. This method can help with other router malfunctions.

Computer (laptop, etc.) does not see the WiFi network

There can be many reasons for such a malfunction, and all of them are approximately equally common. Consider the main possible reasons.

If the network of your router is not displayed on the laptop in the list of available networks, then you need to check that the wireless network module is enabled. You can do this by looking at the adapter settings in the Network and Sharing Center on your laptop. The wireless connection must be enabled. In the off state, it will be grayed out and you will need to turn on the wireless connection. If you cannot turn it on, then you need to check if your laptop has a Wi-Fi switch and turn it on.

If, despite the fact that the wireless connection remains on, but shows the status - No connection, then you should check whether the correct drivers are installed for the Wi-Fi adapter and, if necessary, install them. Drivers must be downloaded from the manufacturer's website. This avoids potential driver incompatibility issues.

In addition, you can try to go to the router menu and change the value for the settings there and change the b / g / n parameter to b / g. If this change helped, then the 802.11n standard is not supported. You can also see in the same settings how the wireless network channel is specified, and if it is there - Automatically, then select the channel from the list.

Other malfunctions

If you often experience disconnections during work, it is recommended to update the firmware of the router. In many cases, this procedure helps to solve the problem.

Sometimes, when working with some Internet providers, to access local resources (torrent trackers, game servers), you need to configure static routes in the router settings. Such settings can be searched on the forums of the provider that provides you with the Internet.

Router power supply failures

Surely, many have already encountered the fact that the weakest point of many routers is their power supplies. They often break due to large voltage drops in the mains and failure of individual elements as a result of long work.

Defective or low-quality elements, a scheme that is not designed for a certain margin, can also lead to breakdowns. There are some typical power supply failures. In this article, we will consider repairing the power supply for the D-Link router. Power supplies such as JTA0302D-E and the like are used for Asus and D-Link routers, designed for an output voltage of 5V and a maximum current of 2-3 A. The appearance of such power supplies can be seen in the figure below.

If we consider the circuit and design of similar power supplies, then this is a circuit of conventional switching single-cycle power supplies. In such circuits, a PWM controller is used to control the operation of a field-effect transistor, which is connected to its output. As a result, the voltage is lowered to the desired value and rectified, and it is supplied to the output. A schematic diagram of such a power supply can be seen in the figure below. In this scheme, depending on the model of the power supply, there may be some minor changes regarding the ratings of individual components. The power supply outputs 5 volts. This voltage should not drop significantly under load (when the router is on).

To repair the power supply, you may need to use a soldering iron, solder, a multimeter, a knife and electrical tape. To open the plastic case of the power supply, you need to cut the glued seam of the case. This operation can be done with a knife, but it is more convenient to use a small drill for these purposes.

If you look at the power supply circuit in Fig. 2, you can see that a 2 amp fuse, a choke, a thermistor and a rectifier bridge of four 1N4007 diodes are installed at the input. If there is a large power surge in the network, then all these elements can burn out. They can be easily checked with a multimeter by measuring their resistance. To smooth the rectified voltage at the output, a high-capacity capacitor - C1 (22 or 33 microfarads) is placed after the diode bridge. This capacitor should be 400 V, no less. If it is out of order, then this can be determined by its appearance, it swells up.

In addition, the positive voltage from the diode bridge is applied to the PWM chip, in this case the UC3843B. This microcircuit is used to control the opening and closing of the P4NK60Z field effect transistor. Often the power circuit of this microcircuit contains a malfunction. This circuit has an electrolytic capacitor C6 and a zener diode ZD1, which is rated for a voltage of 20 volts. This capacitor must be of a certain capacity so that during operation the voltage supply to the microcircuit is always within the permissible operating limits. Therefore, the recommended capacitance is 100uF. If the capacitor is dry, then the capacitance will not be enough to start the microcircuit,

It is quite difficult to determine such an inoperable capacitor by external signs. The small size does not allow you to notice some bulge on its cover. It is possible to measure the capacitance of a capacitor, but often with normal capacitance there is a strong drop in ESR. To check the ESR, special measuring instruments are needed; this cannot be checked with a conventional multimeter or tester.

With voltage drops, the zener diode ZD1 may fail. This can be seen from the darkened (charred) body of the zener diode.

In rare cases, the P4NK60Z field worker may fail. This transistor is supplied with a voltage of 13-15V. from the PWM output. The performance of the field effect transistor can be checked with a multimeter (tester) switched to the diode test mode. On the drain-source channel, the voltage drop is 0.6-0.8 V.

If the voltage at the output of the power supply is 5 V, and when the load is connected, it drops to a value of approximately 2 V., then the electrolytic capacitors at the output of the power supply (C9 and C11) most likely dried up. To eliminate this malfunction, it is necessary to replace the dried-up electrolytic capacitors with working ones with the same characteristics.

In the general case, the main repair steps can be distinguished. If there is no voltage at the output of the power supply, then it is necessary to check for breakdown by measuring the resistance F1, TR, the rectifier bridge. To provide some start-up margin, it is desirable to use the capacitance of capacitor C6 10 uF and rated for 50v, and not 47 uF and 25v. as usual in the scheme.

In cases where the output voltage drops, unstable operation of the power supply is observed, it is necessary first of all to replace the electrolytic capacitors C1, C9, C10, C11.

In addition, you can recommend a few recommendations to improve the performance of the power supply. At the output of the power supply, a resistor with a resistance of 220 Ohm 0.125w is usually installed, filled with a special sealant. This resistor operates at extreme values ​​and therefore gets very hot. Heating causes the capacitor C9 to dry out. Instead of a 220 ohm resistor, it is advisable to put a 300 ohm resistor and a power dissipation of 0.5 watts. If a 10v capacitor C9 is installed in the circuit, then it is better to put the same one instead, but designed for 16v.

After repair, the body needs to be assembled. But you can not glue it, but fasten the two halves, for example, with a screed, so that in the future, if repair is necessary, it can be easily disassembled again.

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Repair ADSL modem DSL-2640U version C1.

Krylov P.V.

In that sample of modems,

Which I came across, about 80% of the faults were of the following kind:
Periodic blinking of all LEDs

periodic reset of ADSL connection


periodic LAN reset
The assumption that these are bad electrolytes in the modem's power supply, in principle, was confirmed. So, we open the modem. We tear off the four rubber bands from the bottom and unscrew the screws.



General view of the modem board in the following photo

The following photo shows the capacitors that you should pay special attention to. They are circled in white. These are 2 electrolytes 2200 microfarads at 25 volts and one 470 microfarads at 16 volts. They are usually swollen, the rubber bands are squeezed out.


If there is an oscilloscope, you can see the level of ripple at the output of the secondary power supply of 3.3 volts, just there is a capacitance of 470 microfarads at 16 V.


Here's a not-so-happy picture. At a voltage of 3.3 volts, the ripple is something around 0.5 volts. We change the capacitance at 470 microfarads unambiguously.


The result of the work.


Conclusions.
The equipment is not the worst, modems very rarely die from external influences, but they are not adapted for round-the-clock operation. Worked - turn off the modem, pull the adapter out of the socket, or better, pull out the ADSL line.

The DSL 2500U modem from D-link is another router of the DSL family, outwardly not much different from its older brother, but significantly inferior to it in terms of technical characteristics.

Router d link dsl 2500u: specifications

A detailed list of technical characteristics of the d link dsl 2500u router can be found in the following illustrations:



Brief overview of the d link dsl 2500u router

Like most routers, there are a number of indicators on the front panel of the d link dsl 2500u router that inform the user about the following aspects of the device’s operation:

  • "POWER" - the presence of power on the router;
  • "STATUS" - the status of the router and possible errors in the system (if the indicator is inactive or, on the contrary, is constantly lit);
  • "LAN" - connection and activity of network devices;
  • "DSL" - DSL synchronization status;
  • "Internet" - informs about the presence of an Internet connection and possible errors (if the indicator is red).

There are four elements on the back panel:

  • "DSL port" - for connecting the router to a telephone line;
  • "LAN port" - for connecting network devices;
  • "Reset" - a button to reset the settings of the d link dsl 2500u router to factory settings;
  • "5V=1A" - connector for connecting the battery.

Installing and connecting a Rostelecom modem

The principle of installing and connecting the d link dsl 2500u router is elementary and is no different from other models:

  • in a well-ventilated place away from heating elements, protecting the modem from direct sunlight;
  • turn off the router (dsl port) connect to the Internet line (telephone cable or cable coming from the splitter);
  • to the "LAN" port;
  • connect the power supply and turn on the router.

Setting up an Internet connection on a d link dsl 2500u router

To gain access to the web interface of the router, use the address 192.168.1.1, which must be entered in the address bar of any Internet browser (the default login and password are "admin").

The illustrations below correspond to the latest firmware version 1.0.50.

When you first enter the router interface, a window will appear asking you to make the initial settings of the router.

You can either use the "Settings Wizard" - in order to configure the d link dsl 2500u router in semi-automatic mode and select only the main parameters, or "manual settings" - in order to "carefully" set all the necessary parameters.

Within the framework of this article, we will consider in detail exactly the manual configuration of the modem - in order to have a more complete picture of the network created by the router.

Setting up a d link 2500u modem using the Setup Wizard

The sequence of actions for automatic configuration of the router is shown in the following illustrations:




Advanced settings for the d link 2500u router

To create an Internet connection manually, open the "Network" menu, the "WAN" section and click "Add".

You will see the "Creating a WAN connection" window: here in the "Connection type" line you need to select one of the proposed options, based on the data that the provider indicated in the contract (the same applies to filling in the username, password and atm interface).

Bridge

  • enter the value of "VPI" and "VCI" - depending on the region and service provider;
  • check the boxes "NAT" and "Firewall".

"PPPoE" or "PPPoA"

Here, in addition to the parameters described above, you should specify:

  • "Username" and "Password" (twice);
  • if desired and necessary, enable the options "Connection on demand", "PPP IP extension", "PPP debug" or "PPPoE forwarding".

"Static IP"

"Dynamic IP"

Nothing is required for this connection type.

Save the settings when you have completed entering the data.

Setting up IPTV

Since the d link dsl 2500u modem offers only one "LAN port", you will have to choose whether to provide Internet access to a set-top box or a computer.

In the "Execution days", "Execution start time" and "Execution end time" blocks, you must specify the time interval during which the deny rule will be in effect.

Go to the next section "URL filter" and check the box "Enable / disable url filter".

You can block both individual addresses and all addresses except for allowed ones.

Select one of the options and click Edit.

The next window contains two lines:

  • "URL address" - here you need to specify the address of the site that will be blocked by the router (or, conversely, added to the allowed ones - depending on your choice).
  • "Port" - port 80 for the "http" protocol.

Thus, this model is not equipped with the ability to create a wireless network - this fact and rather weak technical capabilities sent the "2500U" to a well-deserved "retirement" long ago and removed this model from production.

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The D-Link 2500U modem is very common among ADSL Internet users. Cheap, unpretentious even with bad telephone lines, it is quite suitable to provide a computer with Internet access. Although there are modern cheap Wi-Fi modems on the market, the outdated 2500U without wireless technology support still works in some homes.

On the Internet you can find dozens, if not hundreds, of instructions for setting up this modem. However, there are practically no clear instructions for quick setup and connection to the worldwide network. I will try to correct this situation.

Connecting a modem to a telephone line

Any ADSL modem is connected to a telephone line via a wire with connectors (plugs) such as RJ-25, RJ-14 or RJ-11, that is, the most common telephone wire. What they look like and which fit is well told.

This wire is not connected directly to the telephone socket, as its predecessor did - a buzzing and squeaking, terribly slow Dial-Up modem, but through a special filter - a splitter.

To avoid noise when picking up the handset of the phone, so that the Internet works stably and quickly, you need to connect a splitter. This is a box that filters the signal separately for the modem and separately for the phone. Click on the picture below, there I drew two options for connecting a splitter:

As you can see from the text in the picture, you need to connect the splitter Necessarily. And not just connect, but connect correctly - both the modem and the phone are connected through it to the appropriate connectors.

A common cause of slow, unstable internet is the wrong connection of this little box.

Connecting a modem to a computer

Everything should be simple here. We take the blue cord from the box with the modem, insert one end into the yellow connector of the modem (the color may be different, it does not matter), the other into the same port on the back of the computer. Don't find? Very rarely, but it happens. Then you need to go to the store and buy any network card, any cheap one for 10/100 megabits is enough. Then it needs to be installed in the PCI slot of the motherboard. How to do it is written

If you have Windows Vista or Windows 7, at some point a window will appear with a choice of network type. Select "Public Network". At the same time, you do not need to touch the settings of the network card, everything will be configured automatically. After the correct connection on the modem, the light with the inscription "LAN" will be on (or blinking). Read the fourth part of the article in case of problems, there is a solution to typical problems.

Setting up a modem to connect to the Internet

There are two types of ADSL modem connection - bridge setup and router setup. The difference lies in the fact that when connecting with a “bridge”, the computer itself connects to the Internet, using the modem only for the actual data transfer. When connected by a “router”, the modem connects itself, without the help of a computer, and then “gives” the Internet to the computer.

The advantage of connecting with a "bridge" is that the modem will not be heavily loaded when transferring data. This is useful for high speed (from 6 megabits and above) and frequent use of torrents. Minus - the Internet will turn on only when the computer is running.

The advantage of connecting a modem with a “router” is that it is not necessary to have a computer turned on to connect to the Internet. This is convenient, because to connect to the Internet you just need to turn on the modem.

Of course, I greatly simplified the explanation, I told only the essence. Since I prefer connection "router", further we will talk about it.

To connect D-Link 2500U with a router, do the following:

1) Turn on the modem, wait 20-30 seconds. The "Power" light should come on.

2) There is a small round hole on the back of the modem between the connectors. This is the reset button. Press it with something thin (a match, for example) and hold it pressed for 10-12 seconds. The modem must be turned on during this procedure.

3) Wait 30-60 seconds.

4) Open any browser (Internet Explorer, Chrome, Firefox, Opera - it doesn't matter), enter the address 192.168.1.1

A login and password window will appear. Enter admin in both fields. A page like this should open:

The page may be blue, it doesn't matter. There are a lot of versions of the D-Link 2500U modem, but the settings are always the same. However, like other modems.

If the page does not open, try entering the addresses 192.168.0.1, 192.168.2.1. If you receive a message about an incorrect password, try entering Admin instead of admin in your login.

5) Click Quick Setup on the left (Wizard button in some versions of the modem). See the following:

6) Uncheck "DSL Auto-connect". The window will then look like this:

Only the VPI and VCI values ​​need to be entered here. Each provider has their own. You can find out these values ​​by calling the provider's technical support or by searching for them on the Internet. Naturally, you will have to look for a computer with the Internet or go through the phone. Here the decision is up to you.

The provider "Rostelecom South: Kabardino-Balkarian Branch", which I use, will have VPI and VCI values ​​\u200b\u200bof 0 and 67, respectively, I enter them and click Next.

7) In the next window, select the router mode - PPP over Ethernet (PPPoE) and click Next.

It is also necessary to put a tick on the items that I marked in the picture. The "Enable KeepAlive" setting may be called simply "KeepAlive", and "Retry PPP password" may be completely absent.
Advice to those who use the provider "Rostelecom South: Kabardino-Balkaria Branch" (formerly "UTK Kabardino-Balkaria") - if the Internet does not work after setup, reset the modem settings and reconfigure by adding the letters "@" at the end of the login without a space and quotes pppoe". Perhaps this advice is also useful for other branches of Rostelecom.

Click Next.

9) On the next page there will be settings that you can leave as is:

The only remark: I have met versions of the modem, where some of the settings of the previous page have been transferred to this one. So the values ​​"Retry PPP Password on authentication error" and "Enable keepAlive" will probably be here.

Click Next.

10) You will see settings that are strictly not recommended to be touched if you do not know what they are for:

Press the Save/Reboot button and wait. You can close the page, it is no longer needed. After about a couple of minutes, a light with the inscription “i” or “Internet” will flash on the modem - this indicates that the modem is configured correctly and the Internet is working.

Congratulations, you have set up the Internet!

If something does not work - problems and their solution

Yes, it happens, unfortunately. I will list the most common problems, as well as answer the questions that I have been asked repeatedly, asking for help:

Problem: LAN light is off.

Solution: check that you have firmly inserted the cable into the modem and computer connectors.

Problem: the address 192.168.1.1 does not open.

Solution: Check if the modem's LAN light is on. Turn off the antivirus, firewall - they may be blocking the work. Also take a look at the network card settings:

A) In Windows XP - Start - Control Panel - (Network and Internet Connection - if there is such an icon) - Network Connections - right-click on the "Local Area Connection" icon - Properties, select the line "Internet Protocol TCP / IP" (the checkbox should be), then click the Properties button - check the boxes for Get an IP address automatically, get the DNS server address automatically, OK, OK. The network status should be "Connected", as in the picture below:

B) In Windows Vista, go to Start - Control Panel - Classic View - Network and Sharing Center - Manage Network Connections - right-click on the icon "Local Area Connection" - Properties, select the line "Internet Protocol version 4 (TCP / IPv4 ) - Properties - check the boxes for Get an IP address automatically, get the DNS server address automatically, OK, OK. The network status should be "Network" or "Connected", as in the picture below:

Go back to the Network and Sharing Center and make sure "Public Network" is next to "Local Area Connection":

If it says "Private Network", click on "Settings" and change the network type to "Public".

C) In Windows 7, go to Start - Control Panel - View: Small icons - Network and Sharing Center - Change adapter settings - right-click on the "Local Area Connection" icon - Properties, select the line "Internet Protocol Version 4 (TCP) / IPv4) - Properties - check the boxes for Get an IP address automatically, get the DNS server address automatically, OK, OK. The network status should be "Network" or "Connected", as in the picture below:

Go back to the Network and Sharing Center and make sure "Public Network" is next to "Local Area Connection":

If it's "Home network" or something else, click on this inscription and change the network type.

Note: in the case when, after setting the settings to “automatic”, you still have some kind of error, look for its solution in Google or Yandex.

Question: how to reset modem settings?

Answer:

A) Complete reset of the modem settings - press the button in the hole on the rear panel of the switched on modem for 10-12 seconds. Then wait a couple of minutes - the modem will turn on with factory settings.

B) Removing only Internet settings: open the modem page at 192.168.1.1, password and login admin, go to the Advanced Setup section - WAN (or just WAN in some models) - check the box next to the settings line and then click Remove, Save in turn /Reboot:

Question: I set everything up according to your instructions, entered VPI and VCI correctly - my provider, but there is still no Internet, what should I do?

Answer:

A) Check if the modem is connected correctly. In 90% of cases, the cause is inattention.

B) If the Internet light on the modem is on, but there is no Internet on the computer, something is wrong with the computer. There can be so many reasons and they are all diverse, I can only advise point 2 of the fourth part of this article - set the settings to automatic.

IN) Look at the DSL light on the modem. If it is not lit, it means that the telephone line is not connected. Check the modem connection to the telephone line. The splitter must be connected correctly!

G) Set up the modem, then go back to the modem settings - 192.168.1.1 and take a look at the page that opens. If you have empty in the lines "Line Rate - Upstream" and "Line Rate - Downstream", you have problems with the telephone line or it is not connected at all. Call your provider's support.

D) Reset the modem settings and reconfigure it, only after logging in in the settings add “@pppoe” without quotes and spaces. This is exactly what helps with my provider Rostelecom South.

E) Perhaps your provider uses some specific settings. Look for instructions on the Internet, on the provider's website.

Question: When someone is talking on the phone, the internet is disconnected.

Answer: the splitter is connected incorrectly. Or not connected at all. Don't kill your modem, connect it properly! This is discussed at the very beginning of the article.

Problem: the Internet turns on for a long time - more than 5 minutes after turning on the modem.

Solution: call the provider, the problem is on his side.

Problem: Internet frequently disconnects by itself (Internet light goes off)

Solution: the problem is either on the side of the provider, or you have poor-quality telephone wiring. This issue is resolved with the provider and the telephone company. Call your provider's support.

Problem: the modem often turns off, freezes, the Internet “disappears” (the Internet light is on at this time) or the Internet speed drops sharply from time to time, you can’t go to 192.168.1.1

Solutions:

A) The D-Link 2500U modem, like many other D-Link modems, often overheats. If you feel the top cover of the case, it will be hot. The situation is solved by installing a heatsink on the chip and/or installing a cooler. Examples one, examples two. You can also remove the top of the case and put the modem on the floor - it can help, although not as effectively.
B) If you use the uTorrent program or similar - in its settings, reduce the number of simultaneous connections to 50-70 (I posted a screenshot of the settings). This will reduce the load on the modem.
IN) The power supply may be damaged. If you do not have the necessary tools (multimeter or voltmeter with ammeter) to determine the malfunction, look for similar characteristics - 15 +3 / -2 V, current of at least 0.7 A (I took the advice from here), connect it and check the operation of the router.
G) The problem could be viruses. Check your computer with Dr.Web CureIt.
D) Problems can be in antiviruses too, as well as in firewalls (block access to the modem address). Disable them and check the Internet.
E) The red "Power" indicator indicates power problems or some other hardware problems. There is only one way - to the service center for diagnostics and repair.

Conclusion

The settings I have given will help you connect the D-Link 2500U modem and similar models (D-Link 2600U, 2650U, etc.) to the Internet relatively quickly and without much hassle. Setting up the modem as a “router” will allow you to connect it to any computer that has an Ethernet connector (and these are almost all modern computers) without any settings from the computer - the modem will configure everything itself thanks to the DHCP protocol. But there are many subtleties when connecting ADSL modems, it is simply impossible to cover them in one article, so do not blame me if something did not work out.
I also want to note that my article is primarily suitable for connecting one computer. If you have several computers at home and you intend to connect them all to the Internet at the same time, then the D-Link 2500U modem will not suit you. Of course, you can buy a second network card and connect two computers with a network, allowing the second PC connected to the modem to distribute the Internet, but in this case you need to keep the first PC turned on, which is often annoying or disturbing. Ideally, you need either an additional router in addition to the modem (difficult option, I don’t advise), or another modem with several Ethernet ports to organize a local network between computers (the option is much simpler). For example, D-Link DSL-2650U. In this case, after setting up the modem with a router, you can connect computers through the same Ethernet ports (connectors) to the modem, everything should be configured and work by itself. I will not talk about connecting to such modems using Wi-Fi wireless technology now, because it does not fit into the scope of the article (the 2500U does not have Wi-Fi).

D-LINK DSL-2500U belongs to entry-level network devices. Judge for yourself: there is no wireless communication module, there is only one network port, the processor is modest, the amount of memory is small. The scope of this modem can be described by the phrase "one modem - one computer." There are still many places on the periphery where a connection from Rostelecom is the only way to get broadband Internet access. DSL-2500U was specially developed for the countries of the former CIS, so it will work perfectly even on old telephone lines, the quality of which leaves much to be desired in the provinces. From our article you will learn how to connect it, configure it and make it work effectively.

Package contents and price of the D-Link 2500U modem

The device comes in a cardboard box with a branded orange and black design. Inside are:

The patch cord included in the kit is simplified (UTP4). It has only four signal lines instead of the classic eight, so old network cards may not work with such a cable. Keep this in mind if you own an early 00's computer or an old laptop.

D-Link 2500U has been produced for a good ten years, so it can still be found on sale, although the expediency of buying such equipment is doubtful, because it costs about a thousand rubles, and for this amount you can already buy an ADSL Wi-Fi router. The price of a modem in the secondary market varies widely. A “bare” device without cables and a splitter can be found for 100 rubles. A complete set with a box and a network adapter will cost 500–800 rubles.

Appearance, purpose of indicators and technical characteristics

The modem case is made of matte black plastic with ventilation holes on top. On the front panel there are LEDs for indicating operating modes, and on the back - interface connectors and a socket for connecting a network adapter.

The presence of only one LAN port indicates that this device is clearly not intended for the office.

Table: the purpose of the indicators on the front panel of the modem

Modem Specifications

Several varieties (revisions) of the DSL-2500U were released, which differ only in the type of processor and flash memory. Their characteristics are almost the same.

Table: comparison of models of different versions

ModelrevisionCPUFlash memory sizeFlash typeRAMNumber of network ports
DSL-2500UA1BCM63382MBparallel8MB1
DSL-2500U/BRU/CC1BCM63322MBSerial8MB1
DSL-2500U/BRU/DD1BCM63322MBSerial8MB1
DSL-2500U/BRU/DD2BCM63322MBSerial8MB1
DSL-2500U/BRU/DD3BCM63322MBSerial8MB1
DSL-2500U/BRU/DD4BCM63322MBSerial8MB1

Video: review of the D-link DSL-2500U router

Connecting the modem to client equipment

To install and configure an Internet connection using ADSL technology, you need to follow a few steps:

  1. Connecting a modem router to a telephone line and a computer.
  2. Configuring the network interface of the computer for successful work with the modem.
  3. Configuring Internet connection settings via the PPPoE protocol using the modem's web interface.

Let's examine each of these processes in more detail.

Wiring diagram

The DSL-2500U connection is typical: a splitter filter is connected to the telephone line, and a modem port labeled ADSL is connected to it. The Ethernet port connects to a computer's network card or an input on a wireless router.

The modem router is connected to the telephone line using a splitter

Connecting a modem to a telephone line

During operation, the ADSL modem transmits and receives a broadband signal with a frequency of several megahertz, therefore the connection speed depends very much on the quality of the telephone line. This is especially true of wiring in old houses, where it is made of low-quality single-core "noodles" - a low-voltage telephone wire of the Soviet era. If several telephone sockets are connected in parallel in a house / apartment, the connection scheme must be redone. The splitter is installed on the cable entry to the apartment, and the telephone wiring is already connected to it. If the phone and modem are connected in parallel, the Internet will not work.

Connecting a modem to a computer

If the location of the telephone socket does not allow placing the modem next to the computer, you will have to buy a patch cord of the required length or compress it yourself. Two RJ-45 plugs are crimped on a piece of UTP-8 wire in accordance with the diagram.

The cable for connecting the modem router to the computer must be crimped in accordance with the typical color distribution scheme

Preparing a computer for connection - network adapter settings

Almost any router also works as a DHCP server, that is, it distributes IP addresses to client devices. Addresses are issued from the range specified in the router settings. For this mechanism to work properly, the network adapter must be configured to automatically obtain a TCP/IP address and a DNS server address. On computers running Windows, you may encounter a situation where a static (permanent) address is assigned to a network adapter. This may cause a conflict with another device on the network, which receives the address automatically. The result will be the loss of access to the Wi-Fi network (and the Internet too) on both devices.

To avoid such an error, you need to check the properties of the wireless adapter and switch (if necessary) it to automatically obtain addresses.

  1. Click on the "Start" button with the right mouse button and select "Network Connections" from the user menu.

    Call the network connections section from the user menu

  2. In the network connections window, select the required adapter and use the right mouse button to open its properties.

    Network adapter properties contain TCP/IP protocol settings

  3. Select TCP/IP from the list of protocols and double-click to open its settings.

    All IP address values ​​are set in the TCP/IP protocol settings for the network adapter

  4. Set to automatically obtain the network address and DNS server address, and then click OK.

    The automatic address acquisition mode is set by checking the boxes in the corresponding fields of the TCP / IP properties window

Modem web interface, configuration and access protection

After the computer's network card is configured to automatically obtain an IP address, the modem's WEB interface can be accessed at 192.168.1.1. The username is admin, and the default password is blank, meaning you don't need to enter it. To protect the network from third-party interference, change the access password immediately after the initial modem setup.


Internet connection setup

After the modem is connected to a telephone line, a computer and there is access to the web interface, it's time to set up an Internet connection. We will do this using the example of the largest provider working with ADSL technology - Rostelecom.

  1. Click the Add button and in the new window that opens, specify the VPI and VCI values ​​\u200b\u200bissued by the provider. If you forgot to tell them, you can clarify the necessary data by calling the free technical support line. In the Service Category drop-down list, select the UBR Without PCR option.

    On the first screen of the setup wizard, enter the VPI and VCI parameters

  2. Connection to Rostelecom is carried out using the PPPoE protocol. Select it from the list of protocols.

    Connection to the provider "Rosteleko" is carried out using the PPPoE protocol

  3. From the agreement with the provider, take the login and password assigned to your account and enter them in the appropriate fields of the settings window. Enable the Keep Alive option so that the connection is automatically restored after a connection break.

    Enter the login and password for accessing the Internet, which are specified in the agreement with the provider

  4. On the WAN settings page, enable the Firewall and NAT. Be sure to check the Enable WAN service checkbox. If you plan to watch digital TV on your computer, check the Enable IGMP Multicast option. In the Service Name field, enter the name of the created connection and click the NEXT button.

    Don't forget to activate the firewall and NAT options

  5. On the settings report page, check the correctness of the entered data and click the Finish button. The modem router will reboot and establish a connection with the provider, so you will have Internet in a few minutes.

    After rebooting the modem, a brief report of the settings configured will appear on the screen.

Video: D-Link DSL-2500U setup

Port forwarding

Some users need to access their local network resources from the Internet: home network folders, a picture from a home IP camera, remote administration with Remote Administrator or Team Viewer programs, and dozens of other necessary applications. To organize the possibility of such access, the so-called port forwarding is required, when the router combines an external network port and one of the internal ports. Setting up port forwarding is easy using the modem's web interface functions.


Setting up the modem in bridge mode

The computing capabilities of the DSL-2500U are very modest. If you are using the device in router mode, then even with only one computer connected, programs with a large number of connections (torrent client or web server) can overload your modem. The result will be interruptions in work, and even the freezing of the device. The best way to operate is to put the DSL-2500U into bridge mode and connect it to an inexpensive router such as the DLINK DIR-300.

  1. Open the window with the modem setup wizard (Wizard). Uncheck the DSL Auto-connect box and enter the values ​​VPI=0 VCI=33 in the field that opens. Click Next.

    VPI and VCI parameters must be entered based on the settings of your provider

  2. In the next Connection Type window, select Bridging, Encapsulation Mode - LLC/SNAP Bridging, click Next.

    Set the type of connection to the Bridging network - this will put the modem into bridge mode

  3. In the next window, check the Enable Bridge Service checkbox.

    Activate the Bridge Service option

  4. In the next window, if necessary, you can change the IP address of the modem. If the modem will be used in conjunction with a wireless router, set the address from the range provided by the wireless router's DHCP server. The subnet mask must also match.

    Enter the address to access the modem settings

  5. The final window of the configuration wizard displays summary information. If all values ​​are correct, press the Save/Reboot button to save the settings and reboot the modem.

    Check the data and save the changes if everything is entered correctly

Possible problems and problems with the modem: diagnostics and troubleshooting

The DLINK DSL-2500U is a simple and reliable piece of equipment, but it can also experience failures that prevent normal operation. This is especially noticeable when buying a used modem. The table below lists common problems and their causes.

Table: Typical DLINK-2500U Modem Router Problems

Problem symptomCauseRemedy
Power on indicator is offFaulty power supplyReplace the power supply with a good one. Suitable for any with a voltage of 12V and a current of 0.5A and above
Power indicator glows orangeModem is in rescue modeThe modem firmware is corrupted. Download the new firmware using the patch cord as described in the user manual
DSL indicator flashes continuouslyThe modem cannot communicate with the provider's equipmentCheck the condition of the connecting cables between the modem, splitter and line, as well as the splitter itself. If they are in order - contact the technical support of the provider
Modem restarts every 2-3 minutesThe power supply has failedReplace the power supply with a working one or repair the old one
Internet connection icon not lit, no network accessLogin and password in PPPoE connection settings are entered incorrectlyUsing the web interface, check the account settings and enter the correct parameters
The modem is very hot, the network access speed has droppedThe load on the modem's processor is too highIf it is not possible to reduce the number of connected clients, switch the modem to bridge mode and use it in tandem with a regular router

A few years ago, when I was a client of the Rostelecom provider, a bunch of a DSL-2500U modem and a cheap DIR-300 wireless router worked for me. Despite the fact that the modem was in bridge mode, it got very hot and, as a result, hung up every few hours. Since the modem was already old and the warranty had ended long ago, it was decided to improve its thermal conditions by installing a cooling system. I installed a heatsink from an old motherboard on the processor chip, and cut a round hole in the upper part of the case where I installed a computer cooler. The temperature of the modem dropped significantly, then it worked without failures.

A fan from an old video card will help you forget about overheating of the modem forever

The power supply (network adapter) of the modem operates in an even more severe thermal regime than the device itself. The result is the failure of the filter tanks (capacitors) in the power circuits. If you are at least a little friendly with a soldering iron, you can repair the adapter yourself. A failed capacitor is easy to find: its body will be swollen and deformed.

The first sign of a bad AC adapter is a swollen capacitor.

Video: improving the cooling of the D-Link 2500U DSL modem

The D-LINK DSL-2500 modem router is a time-tested, but very old solution, so if you are only connecting to the Rostelecom (or similar) network, buying it will not be a rational choice, because a bundle of a modem plus a wireless router will cost more than buying an ADSL router with a wireless module. But if you live on the fringes and the state of the telephone lines or the policy of the provider does not allow you to use high-speed tariff plans, the capabilities of the DSL-2500 are more than enough. After all, as the wise ancestors wrote, the old horse does not spoil the furrow.

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