WDS stopped working in 21.02, looking for bug in netifd

[Daniel Haid]

Another update:

I put some logging code into the function interface_add_link. On every 
reboot the function interface_add_link is sometimes called for the 
device wlan0.sta1 and sometimes not.

What I have seen is the following:

When it is not called, the connection works.

When it is called, the bug takes effect and the connection does not work 
or sometimes it still works.

So there seem to be two layers of randomness.

What I have not seen: interface_add_link is NOT called for wlan0.sta1, 
but the bug still DOES take effect. Of course, without infinitely many 
tries I cannot rule it completely out.

I have also been able to trigger the bug with 802.11r disabled by 
turning of the client until the interface wlan0.sta1 disappears on the 
AP and then turning the client on again. But this is also not deterministic.

-----
D.H.