Hi Johannes,

Back with the traces.

First, I was wrong about receiving frames from other STA using same AP. It
was my fault.

Below (see attachment) is a trace from ieee80211_rx_h_sta_process() 
You can see the frames that will update the last_rx field.

Current version will update on all frames due to the OR condition.

Changing it to and AND condition will strip almost all frames away in the
sample.
The result would be that the STA will PROBE the AP each 2 seconds in the
ieee80211_rx_h_sta_process().

In my code I have added a feature that monitors BEACONS from 'my' AP.
When number of received beacons drops below 5 / 2 seconds, I assume out of
range.
I do not know if this is necessary but it gives faster roaming in the
out-of-range scenario.

/Lars