Issue with WiFi and 5 Ghz disapearing

ISSUE FIXED !!!

the problem come from the implementation of 802.11d : wifi location and country ID conflicts.

if there are different wifi Access points broadcasting mixed countries ID, Mac OS may shut down certain frequencies.

Solution at the end of the post   :)))

Just after a restart my MacBook Pro 16 is set to locale ETSi and country code X3

All channels and frequencies are opened.

If i stop and restart the wifi, or the Mac goes in power save mode and turn off the radios.

When it wakes up i got this:

Country code has moved from X3 to ID, and most of the supported channels are gone.

the 5 ghz are all gone

There's a lot of posts about this on the internet, about either adding another AP and setting county code.

Some APs (like mikrotik don't broadcast country codes)

Some posts are about modifying the wifi drivers.

Don't do any of that, the solution is quite simple !!!

I'm now on MacOS 11.0.1 Big Sur.

But i assume the solution is the same on previous MacOS Versions

Go to:  

  --> Apple Menu 

     --> system preferences 

        --> Security & Privacy

           --> Location Services

              --> Scroll down till you find System devices

               --> Click on Details...

                --> UNCHECK WiFi Networking

This will bypass 802.11d implementation and 5ghz will show up right away