How to confine Wi-Fi driver to use IEEE 802.11ac mode and lower?

I have a notebook with wi-fi chip that supports IEEE 802.11ax as most. Below is lspci output.

5d:00.0 Network controller: Intel Corporation Wi-Fi 6 AX210/AX211/AX411 160MHz (rev 1a)

And when I used it in Windows OS I figured out that the download/upload speed was much faster (twice or thrice) when I prohibited to use ax mode and allow to use ac and lower. Maybe owing to some hardware bug.

Some days ago I installed Fedora on the same notebook and have come across the same speed problem. Download and upload speed (speedtest.net) is extremely slow, around 10-20Mbs instead of 80-90Mbs.

I want to solve my problem the way I solved it in Windows. I want to confine linux wi-fi driver not to use ax mode.

I figured out that now driver does use ax mode. Below is result of iw dev link command:

        freq: 5180
        RX: 58469848 bytes (52247 packets)
        TX: 6355149 bytes (26551 packets)
        signal: -59 dBm
        rx bitrate: 408.3 MBit/s 80MHz HE-MCS 8 HE-NSS 1 HE-GI 1 HE-DCM 0
        tx bitrate: 510.3 MBit/s 80MHz HE-MCS 10 HE-NSS 1 HE-GI 1 HE-DCM 0

Compare the difference:

Windows:
Windows

Linux:
Linux

Asked By: Alexey Subbota

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Create a text file named e.g. /etc/modprobe.d/disable-11ax.conf (you can pick any name, as long as it has the .conf suffix and is placed in the correct directory) with the following contents:

options iwlwifi disable_11ax=1

If your Linux distribution loads the iwlwifi driver in initramfs, you will need to update your initramfs file to ensure the setting will take effect at boot.

The initramfs update procedure is different in various distributions:

  • on Fedora, dracut -f seems to be the right command.
  • on Debian/Ubuntu/Mint, update-initramfs -u does the job.
  • on Arch, the command is apparently mkinitcpio… but I don’t know too much on Arch.
Answered By: telcoM
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