I recently had issues with my Raspberry Pi 4 that I used to run Octoprint for my Ender 3 V2 3D printer. The full story of that is for another time. To deal with that issue I decided to use an old Intel NUC6i7KYB NUC I had laying around instead. The goal being it would be faster, and more reliable than the Raspberry Pi.
At first my plan was to re-use the wireless USB adapter, an ALFA AWLS036ACH. Which I had originally used with aircrack-ng for war-driving back in 2016. The issue with it is that it’s wifi drivers, including 8812au-20210629, never got mainlined into the Linux kernel. Having to either manually compile a driver per kernel upgrade, or keeping dkms working just isn’t worth the hassle. Then I ordered an ALFA AWUS036AXML from Amazon. I found it in this list while doing research on USB adapters that have mainlined kernel drivers. In the interim I used the built-in Intel 8260 wireless card. The reason I wanted an external USB adapter is for the higher gain antennas.
In the process of setting up the AWUS036AXML I disabled the built-in bluetooth and wireless via the BIOS of the NUC. The goals were to disable the bluetooth I wasn’t using, and disable the internal wireless card so that the external one could be the only wireless network interface. This is where the problem came in. I booted into Fedora Linux 38 that I had installed on the NUC, logged in, and found it hadn’t connected to wifi. At first I thought I just needed to tweak the settings a bit given that I had just swapped wireless hardware. Instead I found the external wireless adapter was recongized via ifconfig, the driver loaded as expected via lsmod, but it not working via various commands. One of those commands was dmesg.
I found after some troubleshooting I couldn’t connect to a known good SSID, I couldn’t scan for SSIDs, and it was just dead in the water. I tried Googling for suggestions. One of the ones I found suggested running rfkill list. I tried that, but it looked all good. At this point I was all out of ideas, but the rfkill idea gave me another idea. The idea was re-enabling the bluetooth and wireless in the BIOS. I did this, and sure enough the new wireless adapter started working. Then I went back in and re-disabled the internal bluetooth. I found it didn’t make a difference. Then I tried googling for a like story, but couldn’t find one. My theory is that the mechanism that Intel used in their UEFI BIOS to disable their internal wireless card triggers the equivalent of a software wireless kill switch in Linux.