"set interfaces wireless <interface> country-code <cc> " doesn't work, because cfg80211 failed to load regulatory database.
Error log in dmesg:
cfg80211: loaded regulatory.db is malformed or signature is missing/invalid
Workaround:
sudo update-alternatives --set regulatory.db /lib/firmware/regulatory.db-upstream
This can be reproduced even without real hardware:
[email protected]:~$ sudo modprobe mac80211_hwsim [email protected]:~$ sudo dmesg | grep cfg802 [300193.910158] cfg80211: Loading compiled-in X.509 certificates for regulatory database [300193.963289] cfg80211: loaded regulatory.db is malformed or signature is missing/invalid