Perchance this will help someone.

I had fun (no, I didn’t) getting wpa_supplicant working on Arch Linux. I kept getting “deauthenticated from c0:50:8a:99:d6:40 (Reason: 6)”.

The answer was that netcfg was defaulting to giving wpa_supplicant the nl80211 driver as well as wext (-D nl80221,wext).

Adding WPA_DRIVER=“wext” to /etc/network.d/interfaces/wlan0 fixed the issue.