The default wifi country setting can not detect a 5G WiFi signals , whose channel is above 139.

I have not test all the channel, maybe the un-work channel list is bigger. At least,  channel 39 to 63 is OK.

I tried to add one of below lines to /etc/wpa_supplicant.conf,  but have no effect.

country=cn
country=CN
COUNTRY=cn
COUNTRY=CN

The above setting in wpa_supplicant.conf  in Raspbian(Pi's official os)  is OK. 

Or, in other words,  I can modify Raspbian's setting to make Pi 4 detect any 5G WiFi signal.

Is there anythings missing with AGL pi4's wifi component?