I have the same (or a similar) issue. App finds & connects (android) phone to Brennan; then some time later - perhaps not a long time - it may report that it "can't find any devices".
I have fixed the channel for the Brennan on my router; If I input this in via Manual Setup, no effect.
My Brennan is in the same room as the router, so it's not likely a connection issue.
Just removed & replace dongle - yes connection to phone restored.
Paul - do you think dongle itself may be dodgy? Or something in the box itself?
Any help gratefully received.
Apart from this, the B2 is a marvel.
:)
MS