I read on forum that one of few reasonably prices WiFi6 cards supported in x86 OpenWRT is MT7921 so I purchased one (that happened to be MT7921K). I got it recognized by my mini-PC using M.2 -> MiniPcie adapter. It identifies as "AMD RZ608" It is very reasonably priced.
Unfortunately, only drivers available in stock OpenWRT distribution seem to be kmod-mt7921e, kmod-mt7921u and kmod-mt7921s.
Only driver that could initialize the card is kmod-mt7921e. Wireless will turn on and I can see the SSID. But it is not really handled well by LuCi (it reports 3dBm as power) and device will connect to it but TCP-IP stack does not seem to work...I never get DHCP adress and I cannot ping even if I set IP manually.
Is there any external driver I can use or is K-version not supported and I made a wrong choice?
Latest official build is 22.03.5. I checked list of packages in repository for 22.03.5 and as you can see, there are no new MT79321K drivers added there. MT79321E driver has slightly newer version.
Judging by the name, the only difference between those cards would be additional support for 6GHz band and it should be supported by the same driver. Before stating that it doesn't work always try the snapshot build first, as @slh said. What forbids You to try it out?
I just booted from latest snapshot and I was able to connect after installing MT7921E driver! So apparently, something was added lately.
Unfortunately, my setup (UEFI,boot from NVMe, x86) makes it very cumbersome to update versions.
I will now try to boot from latest stable version and see whether it still works.
(it is still reporting 3dBm as power though but I assume it is wonky driver/Luci communication)
Judging from versions of MT7921 packages, a lot has happened since...I could even see difference between 22.3.5 and latest snapshot. Once has 6GHz selectable, other has not.
The kernel suffix has no relation whatsoever to the codebase. It only indicates against which kernel (not even against which wireless stack) that module was built.