So we can better assist you, please provide a brief description of your current setup using this link as a guide.
Make sure to describe your network configuration/topology, including any networking hardware currently in use, so we can have a clear understanding of how your devices are communicating.
Fritzbox 7390, Configuration should be irrelevant cause Tidal works on every computer an Apple TV fine and fast
MacMini, Oppo, iPhone 7
Library details, irrelevant, Library works fine
Reboot the core? Wont do reboot my NAS for that, but I started the Room Server again. Could be that this helped, but I watched not explicit for that. Nevertheless the problem occurs ferequently 1-2 times a week. Yesterday I have to recover my login at Tidal. Why is no direct login to Tidal in room possible? SONOS enables that! ROON have to open a Browser.