Hallo @Dieter_Schaaf,
concerning the FB protocol, the disconnects are caused by a feature of your Fritzbox that can be bypassed only by disabling automatic wifi channel change.
For a fix, please have a look:
increase with the running time of the nucleus. If I keep it connected to the network, it happens more and more often. if i turn it on shortly before the start of my listening session, nothing happens.