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Help needed: After 1 year, 2.4G stop working, 5G works fine (Asus RT-AC68U, TM-1900, Firmware Merlin

Discussion in 'Asuswrt-Merlin' started by hiac, Nov 19, 2017.

  1. hiac

    hiac Occasional Visitor

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    Hi,

    I have some ghost issue hoping you could help me out.

    I got Asus RT-AC68U (TM-1900) exactly 1 year ago, and I follow this instruction to flash Firmware to Merlin 380.65 (instruction: https://slickdeals.net/forums/showpost.php?p=73690012&postcount=3895), I called this 10-step-instruction.

    I notice this issue because my chromecast only support 2.4G.

    About 2 weeks ago, 2.4G wifi stop working, 5G works fine. Some times 2.4G signal doesn't show up in the wifi list. Some other time I can see it but when attempt to connect it error out (I forgot to write down the error message, but I am pretty sure password is correct). Restarting the router doesn't resolve the issue. However 1-2 day later it start to work again.

    Yesterday issue come back, and reboot router doesn't resolve the issue. I changed Control Channel to use 1, 6, 11, none works. I wonder what might be the viable next step.

    1) I search this forum, some suggest to do factory reset.
    Question: after factory reset, should I flash firmware again, by using that 10-step instruction?

    2) I saw this post get a lot of attention:
    [Fork] Asuswrt-Merlin 374.43 LTS releases (V28E2) (https://www.snbforums.com/threads/fork-asuswrt-merlin-374-43-lts-releases-v28e2.18914/)

    I wonder if I should give it a try. If I go this route, should I factory reset first, then follow that 10-step instruction?

    Many thanks for your help!
     
  2. ColinTaylor

    ColinTaylor Part of the Furniture

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    Those "10-step instructions" don't change the firmware, it flashes a new CFE that isn't locked to TMobile. Changing the CFE is a 1-time process after which you can load a non-TMobile firmware of your own choosing.

    1) Just do a factory reset from the web interface. When the router restarts, reconfigure your settings manually. Do not reload settings from a backup.

    2) If you're still have problems try updating your current firmware to the latest version.
     
  3. hiac

    hiac Occasional Visitor

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    Hey ColinTaylor,

    Many thanks for your help! I am going to give it a try :)
     
  4. hiac

    hiac Occasional Visitor

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    Just do a reset, and 2.4g wifi show up, but can't connect to it. show "Unable to join the network"

    I found a similar post, but it doesn't offer solution.
     
  5. gpz1100

    gpz1100 Occasional Visitor

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    Did you try reflashing the firmware? It's hard to imagine read only firmware getting corrupted, but since this is a flash chip after all, it is possible. If it's still failing then it could be a hardware issue with the device itself.
     
  6. ColinTaylor

    ColinTaylor Part of the Furniture

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    Make sure you have typed the password correctly in the router's web interface (Wireless > General). Remember to click "Apply" after entering the password for 2.4GHz. Then switch to 5GHz, enter the password there and hit "Apply" for that.

    On your client device go to the network settings and "Forget" the network, then try to connect to it again from scratch.

    EDIT: Don't use any non-alphanumeric characters in your password. Just a-z, A-Z and 0-9.
     
  7. hiac

    hiac Occasional Visitor

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    Hi gpz1100,

    I suspect it's hardware issue too. I found a post with similar issue:
    https://www.snbforums.com/threads/cant-connect-to-2-4g-please-help.23276/

    after upgrade firmware, issue still doesn't go away
     
  8. hiac

    hiac Occasional Visitor

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    Hi ColinTaylor,

    Thank you for your help. I tried your suggestion, issue still doesn't go away
    I suspect it's hardware issue . I found a post with similar issue:
    https://www.snbforums.com/threads/cant-connect-to-2-4g-please-help.23276/
     
  9. ColinTaylor

    ColinTaylor Part of the Furniture

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    @hiac Yes it does sound like a hardware fault. Surprising after only one year, but these things happen. I'm assuming it was new when you got it.

    Perhaps it's overheating. Is the router in an unusually hot environment or does it lack ventilation? Go to Tools > System Information and check the temp's. Here are mine by way of comparison (in a slightly cool environment).

    2.4 GHz: 50°C - 5 GHz: 52°C - CPU: 82°C
     
  10. azdps

    azdps Occasional Visitor

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    ASUS router temperatures for the CPU, 2.4ghz and 5ghz bands have been running high for several years now. Unless you have been actively cooling your router since you've had it with an external fan or something similar I suspect your issue could be one of these issues:

    • Premature hardware failure
    • Wireless client(s) causing havoc (per RMerlin)

    Could be either one but I'm leaning towards hardware failure since you've been using the same firmware for a considerable time then all of a sudden your 2.4ghz band isn't working like it should. Sure some ASUS routers last for several years with high temperatures but at the same time others fail prematurely.
     
  11. hiac

    hiac Occasional Visitor

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    Hey ColinTaylor,

    Thank you for staying with me on this issue.
    temperature looks ok
    2.4 GHz: 49°C - 5 GHz: 50°C - CPU: 75°C
     
  12. hiac

    hiac Occasional Visitor

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    Hey azdps,

    Thank you for your insight. temperature seems ok: 2.4 GHz: 49°C - 5 GHz: 50°C - CPU: 75°C
    do you have reference/link to "Wireless client(s) causing havoc (per RMerlin)"
     
  13. ColinTaylor

    ColinTaylor Part of the Furniture

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    When you have the problem with 2.4GHz it would be useful if you could log into the router (using a wired connection obviously) and show us what you have under System Log > Wireless Log.

    It's a bit of a long shot but you could try installing John's firmware to see if that makes a difference. If you install one of the legacy versions it uses a different wireless driver, so that would be an interesting test. I would suggest V28L2. You'll need to use the Asus Restoration Tool to flash the firmware though.
     
  14. azdps

    azdps Occasional Visitor

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  15. hiac

    hiac Occasional Visitor

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    Hey ColinTaylor and azdps,

    I installed V28L2, and 2.4G signal started to work.

    I really appreciate your spend time with me to troubleshoot this :)

    Happy Thanksgiving!
     
  16. ColinTaylor

    ColinTaylor Part of the Furniture

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    Well that's good news. Given what you said before it might only be temporary and the problem may reoccur. He's hoping that's not the case.

    Let us know how you get on.
     

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