Router hitch: TKIP&AES

I updated my PC the other day, rebooted, and…my wifi stopped working. After verifying that my /proc/config.gz == /usr/src/linux/.config, I was at a loss.

In the wpa_supplicant logs:

wlp0s20f0u3: 22: fc:4a:e9:4f:8f:c9 ssid='foo' wpa_ie_len=26 rsn_ie_len=24 caps=0x1411 level=-91 freq=2437 
wpa_parse_wpa_ie_rsn: invalid group cipher 0x8 (000fac02)
wlp0s20f0u3:    skip - SSID mismatch

foo was indeed my ssid, what does it mean that it "mismatched"? Plus my other devices could connect just fine. I thought the update had broken something between the kernel, firmware or something user-space.

I was impatient - I needed to use my PC. Thinking that my specific network card was the problem (Intel Corporation Cannon Point-LP), I decided that since I had a Realtek USB WiFi dongle (Ralink Technology, Corp. MT7601U) I could use that in the meantime and deal with this breakage later.

I compiled the MT7601U module, looking forward to continuing with my rudely interrupted life. I couldn't connect with the dongle either. In fact, wpa_supplicant couldn't seem to see my ssid at all!

I rebooted the router, chastising myself for not doing that in the first place. But there were other confounding cicrumstances - such as my just-completed upgrade, that made me not suspect the router.

The reboot didn't resolve anything. Google was informative, but not helpful.

Eventually I thought "invalid group cipher 0x8" surely means something was off with the encryption - maybe the router's firmware had updated? I logged into the router, looking for anything on encryption:

I toggled the encryption-mode from "TKIP&AES" to "AES", and voila! My oddyssey was over.