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I have TP-Link WiFi router where I have enabled 2.4GHz and 5GHz. Suddenly, I find out, I cannot connect to 2.4G from my laptop, so I started investigating. From my phone, I am able to connect without any problem. When I tried to connect from laptop I receive dialog with reenter password request.

I found out two suspicious things.

First one, from dmesg it looks like it is authenticated but it failed on association.

$ dmesg -T -w [So lis 27 14:37:11 2021] wlp5s0: authenticate with d8:07:b6:2b:ae:e4 [So lis 27 14:37:11 2021] wlp5s0: send auth to d8:07:b6:2b:ae:e4 (try 1/3) [So lis 27 14:37:11 2021] wlp5s0: authenticated [So lis 27 14:37:11 2021] wlp5s0: associate with d8:07:b6:2b:ae:e4 (try 1/3) [So lis 27 14:37:11 2021] wlp5s0: associate with d8:07:b6:2b:ae:e4 (try 2/3) [So lis 27 14:37:11 2021] wlp5s0: associate with d8:07:b6:2b:ae:e4 (try 3/3) [So lis 27 14:37:11 2021] wlp5s0: association with d8:07:b6:2b:ae:e4 timed out [So lis 27 14:37:22 2021] wlp5s0: authenticate with d8:07:b6:2b:ae:e4 [So lis 27 14:37:22 2021] wlp5s0: send auth to d8:07:b6:2b:ae:e4 (try 1/3) [So lis 27 14:37:22 2021] wlp5s0: authenticated [So lis 27 14:37:22 2021] wlp5s0: associate with d8:07:b6:2b:ae:e4 (try 1/3) [So lis 27 14:37:22 2021] wlp5s0: associate with d8:07:b6:2b:ae:e4 (try 2/3) [So lis 27 14:37:22 2021] wlp5s0: associate with d8:07:b6:2b:ae:e4 (try 3/3) [So lis 27 14:37:23 2021] wlp5s0: association with d8:07:b6:2b:ae:e4 timed out

Second, I let the wireshark to capture everything on my wireless interface, but there is nothing captured on 2.4G band. I tried it with my 5G network and it works fine, wireshark has been able to capture packets.

I checked MAC Address of Wi-Fi router, it's OK. My laptop is not on blacklist and in syslog of router, there is nothing.

I create a hotspot from my mobile phone on 2.4G band, and it works nicely. I could see logs in wireshark and dmesg too.

From my point of view, my PC is able to use 2.4G Wi-Fi, my Wi-Fi router works, but my PC cannot connect to it (only to 5G works).

I also update and upgrade system.

How can I debug this issue and find out the root cause and fix it?

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  • Bluetooth interference? They work on same Band. Its not fix but try turning down bluetooth and see if works to see if its the cause. Commented Dec 22, 2021 at 12:17
  • 1
    Is "suddenly" related to some upgrades you did on your computer? If yes, I'd suspect firmware/driver issues. Commented Dec 22, 2021 at 18:09
  • one debugging technique, have you tried to connect to it with more distance, where the 5Ghz breaks, and 2.4 is still good? Sometimes these devices choose 5 over 2.4, by default, and im also wondering if maybe its the router also bumping it because of this, which wouldn't be nice. Commented Dec 22, 2021 at 20:10
  • can you test with WPA2/WPA3 ? Commented Dec 23, 2021 at 16:04
  • I tryied turn of bluetooth, the same result. Suddenly - no after upgrade. Most of the time, I am on cable or near wifi (4m) so I prefer 5G. From time to time, I move to the room where 5G signal is weak (distance and walls) and I figure out I cannot connect to 2G, even when I am in front of router. I tested to manually remove 5G network and test only with 2G - does not help, With other devices like phone or other notebook (windows) it works fine. Commented Dec 24, 2021 at 15:12

1 Answer 1

Reset to default
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FWIW i had the same problem on 5.15 kernel on an Ubuntu 22.04 and this post helped, but note the updated option syntax so i added the comment and options line

# fix for 2.4ghz options iwlwifi 11n_disable=1 # remove the iwl?vm module and then iwlwifi.

to /etc/modprobe.d/iwlwifi.conf and rebooted and it worked for this one specific AP on 2.4GHz.

Some further suggestions can be found in this thread but unfortunately its locked by now.

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