Monday, November 23, 2015

Supercharge your DLink DSL-2750u with OpenWrt

This articles talks about how to install OpenWrt on D-Link DSL-2750U-C1 router. if both terms are new for you, then probably you are in the wrong place. But for the curious, DSL-2750U is a wireless ADSL2 router with 4 LAN ports and the product page is here and OpenWrt is a Linux distribution for embedded devices with a special emphasis on routers.

Note: This article talks only about DSL-2750U-C1 which is based on Broadcom chipset and the steps will not help for DSL-2750U-U1, which is based on RTL chipset. Please contact openwrt if you happen to have the latter.

Disclaimer

Please pay attention as there is a fair chance that you might brick the router and make it completely useless. You are completely on your own and I am not responsible for any direct or indirect consequences for following these steps or any recommendations that I a make. So turn back now if you are unsure.

Why OpenWrt

So you don't go by warnings, lets risk it then.
The benefits of installing OpenWrt is that you can do almost anything with your router respecting the hardware capabilities. OpenWrt is still limited by the fact that there is no ADSL support, so if you are looking to use as an ADSL router then you are better off with the default firmware.

There is already a long list of OpenWrt supported routers but unfortunately as of this writing this particular model is not supported. This router is completely supported by the OpenWRT firmware, see below for details. My main interest was that I have this router and want to use this to extend  my wireless connection to an old wired desktop computer.

How to flash

The trick is that  you can use the firmware for A4001N for flashing this device, like this one here,  https://downloads.openwrt.org/chaos_calmer/15.05/brcm63xx/generic/openwrt-15.05-brcm63xx-generic-A4001N-squashfs-cfe.bin.
I have picked the latest firmware linked on this page here and the wireless and ethernet work fine with this firmware. My primary use of the unit is as a router, connecting wirelessly to my home wifi and providing connectivity to my desktop (no wireless capability) and printer in my garage.

For flashing, the OEM firmware-update through the web interface will not work. You have to use the CFE (bootloader) web interface (hold on reset button while powering on the router), refer https://wiki.openwrt.org/doc/techref/bootloader/cfe#using_cfe_web_http_server.

Just to summarize the flashing steps,
- Assigning static ip to your machine which is connected to router using a LAN cable
- power off the router, press the reset, power on the router *keeping* the reset pressed, release after few seconds when the light goes red
- Point your browser to 192.168.1.1 (remember to clear caches of the browser if you have problems in accessing the page)
- upload the firmware through the web interface, it will take few minutes and restart
- Remove the static IP for your machine and configure to do DHCP and Enjoy

How did I find it

 Initially, I tried with the closest-matching name logic and picked up the DSL-2740 firmware.  I was able to flash it and the ethernet port worked but the WiFi didn't as it had an Atheros chip. I slipstreamed various bcm drivers but it all failed in the step "get the SPROM". Later I worked through the code and found out that the board files have static  SPROM entries for each of the bcm43xxx chips. So I had to pair with a OpenWrt firmware configuration which matched the SoC 63xx and wifi chip BCM43225, so that it can use the static SPROM definition.  This is how when I found A4001N as one such configuration. I had to use the serial port to examine the boot loader and kernel output. I used an Arduino Uno for connecting to the serial port of the device  and minicom terminal (115200bps, no-hw/no-sw flow control, 8bit, 1-stop bit) in Linux to capture the output/input.


Every now and then I see questions in OpenWrt forums about this device, so thought of sharing this info hoping to be useful for someone. Thanks for reading.

69 comments:

  1. on T1 hardware version, none of setting will save after reboot

    ReplyDelete
    Replies
    1. Enomem: Supercharge Your Dlink Dsl-2750U With Openwrt >>>>> Download Now

      >>>>> Download Full

      Enomem: Supercharge Your Dlink Dsl-2750U With Openwrt >>>>> Download LINK

      >>>>> Download Now

      Enomem: Supercharge Your Dlink Dsl-2750U With Openwrt >>>>> Download Full

      >>>>> Download LINK 5Y

      Delete
  2. Hi Syaifull,
    I dont think this is specific to the details I have posted. If you found issues using openWRT, please raise a bug report in the openWRT forum.

    ReplyDelete
  3. hello sir my router is dsl-2750u/u1 based on rtl8676 . how can i get openwrt for it . please reply :)

    ReplyDelete
  4. how do i acces the cfe mini web server
    thanx in advance

    ReplyDelete
    Replies
    1. There is a CFE web server enabled in the router, which can be accessed as explained here, https://wiki.openwrt.org/doc/techref/bootloader/cfe

      Delete
    2. thanx man i was able to succesfully intall the open wrt without any consol
      but however im having trouble with repeating a wifi network
      thanx in advance

      Delete
    3. I use my router as a repeater to connect my wired desktop
      machine. You can find your required configuration here https://wiki.openwrt.org/doc/recipes/relayclient
      Once you find the required configuration, use google
      to your hearts content

      Delete
    4. thanks man
      now im able to put this useless router to work

      any luck on putting dd wrt or tomato in this router

      Delete
    5. Hi Rodney,
      I never tried ddwrt or tomato firmware. I am not sure if they are supported.

      Delete
  5. Hi enomem,

    I have the Dlink 2750U U1 revision router which I want to use as a repeater wirelessly. I didn't find any option to do that in the default firmware. A search on Google landed me here. The cpu in my model is a realtek one.

    Is there any hope that the above firmware will work on it?

    If you can mail me at anas.recrufest@gmail.com
    Thanks!

    ReplyDelete
  6. The Same Router and this firmware doesnt work. Shows RED Power Light and reboot bacck to dlink firmware

    ReplyDelete
  7. I happen to have the C1 revision and as many have mentioned earlier, doesn't look like the firmware support the RLT SoC. I think the best bet would be to ask the openwrt forum. Since this is D-Link is using opensource s/w (kernel and filesystem), they should release the source and that might also give the developers some clue on how to add the support.

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  8. Wireless n not working with openwrt

    ReplyDelete
  9. Thanks for all your work really useful
    I have question I want to use this router as ADSL and tried many firmware but non of them has working filter URL or MAC any idea how to get it work or any firmware you know has working filter ...
    Thanks in advanced.

    ReplyDelete
    Replies
    1. Openwrt firmware does not support ADSL. So in that case your best bet is to use the d-link firmware.

      Delete
  10. I tried to flash dis firmware.. But it failed.. Pls anyone I want custom firmware.. Help me pls

    ReplyDelete
  11. Just flashed the firmware in Movistar Chile "NUCOM R5000UN" DSL router that is like a clone of DSL-2750U, very similar in hardware (SoC BCM6328, BCM4322 WiFi chip). WiFi is working, but as some people notice, config changes are not saved.

    ReplyDelete
  12. Hi Marcianisto,
    Thanks for the info. Is this firmware better than the stock DSL firmware ?

    ReplyDelete
  13. typecastx has left a new comment on the post "Supercharge your DLink DSL-2750u with OpenWrt":

    Hi enomem, first of all thank you for this very useful info. I have the same router as yours, DSL-2750u C1, everything works fine except WAN. Im unable to connect to my ISP using the WAN port, as if it acts like any of the available LAN ports. Tried 'cat /etc/config/network' and the WAN config is nowhere to be found. Any idea?

    ReplyDelete
    Replies
    1. Hi typecastx, Glad that you liked it. I never tried the WAN part (where ISP providers RJ45 goes) for the purpose of connecting to ISP. I thought it was not supported by openWRT.

      Delete
  14. Hi enomem

    I have uploaded the firmware you link to, and also the latest fimrware (openwrt-15.05.1-brcm63xx-generic-A4001N-squashfs-cfe) but i get an error when its finished uploading the firmware and it reboots in openwrt.

    The router fails to assign an ip address to the nic its connected to on the lan port.

    I've tried manually assigning an ip address but with no luck.

    Im using the GAN5.CZ56T-B-NC.NZ-R4B032.EN(NB604N)_upgrade firmware currently .

    Any help on getting this router to work with openwrt is welcome.

    ReplyDelete
    Replies
    1. Hi Emanuel,
      Sorry for the late reply. Do you know what hardware version you are running this ?

      Delete
    2. The router is not exactly a dlink, its a nucom r5000UN
      which is said to be equal to the dlink model you are upgrading.

      The model
      http://i1303.photobucket.com/albums/ag149/6uoW/58c44c93-bf93-41d3-8acb-185817a53087_zps0hfrxuei.jpg

      What the board says about the hardware version
      http://i1303.photobucket.com/albums/ag149/6uoW/20170228_104519_zpsavc0wtm1.jpg

      Delete
    3. Hi,
      The hardware from photo matches the wiki here, https://wikidevi.com/wiki/D-Link_DSL-2750U_rev_C1 the DSL 2750u C1. So technically the images should work.

      Do you remember what exact error did you get. I remember there was some checksum checking against your hardware revision.

      Delete
    4. Well I flashed the router through the web interface, and that part worked well.

      After flashing i tried to access the router, but it wont assing me an ip address.

      thats as far as i went.

      then i flashed back to original firmware.
      i did the process several times, same result.

      Delete
    5. Hi
      So you mean to say even with the original firmware, the device is not working ?

      >After flashing i tried to access the router, but it wont assing me an ip address.

      Did you mean you tried plugging a cable and accessed the machine ? I think the best bet is to post in openwrt forum and a kernel log will be very useful to see the problem.

      Delete
    6. This comment has been removed by the author.

      Delete
    7. Hi Manuel. Can i have a copy of the original firmware you had. Thanks man.

      Delete
    8. >So you mean to say even with the original firmware, the device is not working ?

      no, the router works with a compatible original firmware (dont recall wich one is it atm).

      But when you flash it with the firmware you provide it wont assign an ip address to the clients connected to the LAN, so i cant access it through web admin.

      I repeat this happen only with the firmware you provide, the router works fine with the original firmware.

      I cant post at openwrt bc i cant access the router, so i cant have the log.

      Delete
  15. This comment has been removed by the author.

    ReplyDelete
  16. Hi all,
    I flashed 3 different DLink DSL-2750u T1 with more than 9 images from :
    https://downloads.openwrt.org/chaos_calmer/15.05/brcm63xx/generic/
    https://downloads.openwrt.org/chaos_calmer/15.05.1/brcm63xx/generic/

    All bin files boot up fine after flashing from CFE web interface, but all flashed images are read only (no settings are saved after reboot of device).
    I have many openwrt devices and only the DSL-2750u has this illness.

    Can anyone point me to something I can do to try to fix this ?

    I tried the ssh into the device and running "mtd erase rootfs_data" like some forums say but it didn't help.

    ReplyDelete
    Replies
    1. Hi Necro,
      Were you able to find the hardware specification for DLink DSL-2750u T1 ? I would like to see if they have the same chipset as C1

      Delete
    2. Hi enomem,
      Sorry for the late reply, I had to wait until I was at my lab to crack one of the dlinks open.
      System on a chip is : Broadcom BCM63281KFBG
      Ram chip : hynix H5PS5162GFR-S5C 126A
      on separate add-on board : Broadcom 8CM43225KML6

      I’m just stumped why all the images you flash on this router run as read only, even if you give load a openwrt image the update function also doesn’t work sins it uploads the image and after reboot it’s still on the same openwrt image that you flashed from CFE web interface.

      Delete
    3. Hi Hexes,
      Thanks for the chipset details. It matches the same as https://wikidevi.com/wiki/D-Link_DSL-2750U_rev_C1 the DSL 2750u C1 hardware, which means the stuff should work.

      I dont really remember which partitions were readonly and readwrite. I would assume atleast the partition which saves the configuration data should be read-write and rest of them read-only. To complicate further the mount might be a 'union fs' where read goes to one partition and read-write goes to another partition. I will make sure to check how my mounts are arranged in my device and report back.

      So if I understand you correctly - it is only that your settings are not saved but otherwise your device is up and running.

      Delete
    4. Yes, device is running vary nicely on the image and everything responds and works.
      My only oeps is the settings part.
      Someone asked me to do “mtd erase rootfs_data” in ssh to try to sort the problem but it didn’t work. It seems like the image from rom is loaded to ram and only the ram data is edited and as soon as you reboot it just loads the image from rom back into ram with the default settings. Hope the info might help, I really like the flexibility of the openwrt system.

      Delete
    5. Was the solution to this problem found?

      Delete
  17. This comment has been removed by the author.

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  18. does any usb 3g dongle work for you on this?

    ReplyDelete
  19. Hi, thanks for this informative post. I had accidentally 'bricked' the device (DLink 2750u C1) and most probably have the CFE bootloader overwritten as I don't see any LED light turning on when I supply power. I have bought a Serial to USB connector but need help in figuring out the exact Tx/Rx pins of the router. Can you please guide me on the same or is it possible for you to upload the image of the router attached with serial cable in high-resolution (as the image in your post is very tiny to figure out the actual cable configuration).

    ReplyDelete
    Replies
    1. Hi Prakhar,
      Sorry to hear that you bricked the device. I have a slightly better picture and I can send it to you if you would like. This was a header near to the external connectors and it had GND inidicated on it.

      You can probe and find the pins, but make sure you
      * connect the GND first and also
      * your connector can handle the level shift (RS232-TTL/CMOS). I got around with a resistor but recommended way is a level shifter.


      Again I am not sure if the serial console will help. If you erased the firmware, JTAG header must be what you should be looking for. But I might be wrong, there might be clever ways to send the firmware through serial. Also openwrt has a page on bricked devices.

      Let us know how it goes.

      Delete
  20. Hi Fausto,
    A clarification on your question, did you mean you have updated the router with OpenWRT firmware ? In that case you might need a arduino as you already have a ssh login to your router.
    Try
    ssh root@192.168.1.1
    (or modify to suit your circumstances)

    I have faced a similar situation with my wifi driver as it 'silently' goes to disconnect. You can check dmesg to see if you are getting any message. Experimenting with a different driver solved the problem.

    If you still think you need a arduino serial port, please refer to my reply to 'Prakhar Prasad May 2, 2017 at 9:09 AM'

    Thanks

    ReplyDelete
    Replies
    1. you might *not* need an Arduino - silly typo, sorry

      Delete
  21. Hey thanks bro.. I did the installation as you described and I could receive the signals and repeat to Laptop via Ethernet.
    However, The router's wifi is now gone and the router doesnt get listed anywhere. I tried adding a 'Master' WiFi interface. That din help either.. If i could achieve that I can effectilely use this device as WiFi-2-WiFi repeater...
    Could you please suggest if this is possible?

    ReplyDelete
  22. Image uploading failed. The selected file contains an illegal image.Need reboot
    please helpe me

    ReplyDelete
    Replies
    1. Which image you have tried ? What hardware version are you talking about ? More information please.

      Delete
    2. https://downloads.openwrt.org/chaos_calmer/15.05/brcm63xx/generic/openwrt-15.05-brcm63xx-generic-A4001N-squashfs-cfe.bin
      i used this image for flashing. and i am using dsl-2750U HW Ver. J1 FW Ver.1.00_R1994_20170317

      Delete
    3. Product: DSL-2750U Firmware Version: ME_1.00

      Delete
    4. Hi nomi,
      Thanks for the info. I am not sure if you have the same hardware as supported by that image. I have an old hardware DSL-2750U-C1, so not sure if they are based on the same chipset.

      You could try newer images of openwrt, at the time of my writing it was 15.05. And make sure you have a backup copy of your current firmware, just to be on the safe side.

      Delete
    5. This comment has been removed by the author.

      Delete
  23. Hello man! Thanks for sharing this :)
    It worked very fine with my DSL-2750U-C1
    The only thing i can't find is where to configure the WAN to access internet?

    ReplyDelete
  24. thanx bro great job it works ;)

    ReplyDelete
  25. Hi enomem,
    USB port working on dsl 2750u?

    ReplyDelete
  26. I have a C1 HW , Is it safe to use the latest firmware ?

    https://archive.openwrt.org/releases/17.01.4/targets/brcm63xx/generic/lede-17.01.4-brcm63xx-generic-A4001N-squashfs-cfe.bin

    ReplyDelete
  27. Is there any download link for 2750u u1

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  28. Hi! I have flashed the file you had shared and everything is well and good except the fact that my router has forgotten its mac address and is showing the base mac address as 00:10:18:00:00:00.

    Is there a way I can write the original mac address on the system? Please help me.

    Thanks.

    ReplyDelete
    Replies
    1. Have put this up here as well: https://stackoverflow.com/questions/51456130/broadcom-chipset-router-reset-base-mac-address-openwrt

      Delete
  29. I am not able to use the router in repeater mode and transmit wifi.
    I have configured repeater mode and if I connect via LAN I can get the net but unable to get WIFI.

    ReplyDelete
  30. CAN YOU PLEASE GIVE US A PHOTO OF THE CIRCUIT BOARD>
    I NEED THE VALUE OF THE INPUT RESISTORS.

    ReplyDelete
  31. I have a dsl2750u V1.....the firmware doesn't seem to work.. its like i update the firmware ..a red light glows and it reboots in dlink firmware

    ReplyDelete
    Replies
    1. Hi Xavier, Could you try the latest firmware that I have updated above ?

      Delete
    2. 2750U V1 tried the latest firmware, for ...A4001N.... 19.07.3 and 19.07.4, invain. Not getting updated with CFE upload, stuck at red light for ever. Restart gives back linksys firmware

      Delete
  32. I am not able to flash the firmware file. Can you please help me flash it. And will flashing this firmware enable my 2750U modem to be as a wireless repeater?

    ReplyDelete
  33. Hello, First, Thank you so much for this build. I am using dsl-2750u with hardware version i1 and I just wanted to know whether I can use it.

    ReplyDelete
  34. i need help
    i have RTL 8676
    someone have a firmware with wds?

    ReplyDelete