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Dual booting Ubuntu and Windows causes the WiFi card to not be detected sometimes.

The behavior appears to be random. Sometimes it fully works, sometimes it does not.

After hours debugging I found a workaround that is presented in the answers section. However I cannot explain why it solves the issue.

This may be related to the problems reported here: https://ubuntuforums.org/showthread.php?t=2426298

My setup:

Dual boot of windows 10 and ubuntu 20.04 (it appears to also be a problem in 18.04)
CPU: AMD Ryzen 9 3900X
Motherboard: Aorus x570 PRO wifi
Wifi hardware: Wi-Fi 6 AX200

When wifi appears successfully on Ubuntu I can see the following wifi related loaded modules:

$ lsmod | grep iwlwif
iwlwifi               331776  1 iwlmvm
cfg80211              704512  3 iwlmvm,iwlwifi,mac80211
  • 1
    Isn't this the real solution? wireless.wiki.kernel.org/en/users/drivers/… Welcome to Ask Ubuntu. – chili555 Aug 28 at 15:46
  • Yeah, this is what I did in the end. Wish I had found this link a while back. However, I have dual boot other (older) platforms before and this is the first time that I ran into this problem (windows fast boot interfering with wifi on ubuntu). I am curious to know why this happens? – nico Aug 28 at 15:53
  • "With this feature enabled, Windows don't really shut down the entire system, but leaves things partially running so you can start the machine faster again." Among other things, Windows has control of the wireless card and won't release it with fast boot enabled. – chili555 Aug 28 at 16:35
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I have ran into similar issues. Wifi would sometimes work, sometimes stop working after booting to Ubuntu in a dual boot system, which appeared to be random.

For me, the solution is to issue a Full Shutdown of Windows before booting into Ubuntu. This can be done by holding the shift key and pressing the shutdown button, or by clicking restart.

If you do not do it, windows fast boot will remain enabled and two problems will appear when booting on Ubuntu:

  • My shared data partition is mounted as read only
  • Wifi network card is not detected. Looking at the loaded modules, cfg80211 does not appear to load properly.

Issuing a full shutdown on windows prevents the problem from happening.

My setup:

Dual boot of windows 10 and ubuntu 20.04
CPU: AMD Ryzen 9 3900X
Motherboard: Aorus x570 PRO wifi
Wifi hardware: Wi-Fi 6 AX200
# Partitions on of my system:
/dev/nvme0n1p1     529M Windows recovery environment/dev/nvme0n1p2     100M EFI System
/dev/nvme0n1p3     16M Microsoft reserved
/dev/nvme0n1p4     194.7G Microsoft basic data
/dev/nvme0n1p5     556.7G Microsoft basic data (Shared partition between the 2 OS)
/dev/nvme0n1p6     201.9G Linux LVM  (with separate volumes for root and home)
$ modinfo iwlwifi
filename:       /lib/modules/5.4.0-42-generic/kernel/drivers/net/wireless/intel/iwlwifi/iwlwifi.ko
license:        GPL
author:         Copyright(c) 2003- 2015 Intel Corporation <linuxwifi@intel.com>
description:    Intel(R) Wireless WiFi driver for Linux
...
firmware:       iwlwifi-cc-a0-50.ucode
...
depends:        cfg80211
name:           iwlwifi
vermagic:       5.4.0-42-generic SMP mod_unload 
$ sudo lshw -C network
  *-network                 
       description: Wireless interface
       product: Wi-Fi 6 AX200
When it is working:
$ lsmod | grep iwlwif
iwlwifi               331776  1 iwlmvm
cfg80211              704512  3 iwlmvm,iwlwifi,mac80211

Currently I cannot pinpoint why this solves the problem, but I hope this information can help other people.

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