DickyDutch Thanks, I found it. The problem was the the check for how long the song has been played was done after the rewind if have a fadeout of 0 (I did test this combination with a fade out). Will be fixed in the final release.
JDSMUSIC Do I understand correctly, that the network session has been terminated while the host has been playing a song? Hm, that should not happen. If the screen is locked while playback is stopped, a bunch of battery saving features of iOS kick in an the network session is terminated. I can't prevent that. But during playback, the session should stay active even if the screensaver kicks in.