My Sonos Beam and speakers playing through the AppleTV were working before I updated the AppleTV to tvOS 12, and the iPhone / iPad to iOS 12. I frequently streamed from my iPhone, iPad and older iMac without any problem. I use Sonos as a sound system for my AppleTV. That was working fine before the update as well. I can only play to Sonos via the Sonos app. If I try to play through the ATV or the iPhone / iPad, I get a message that it won't connect to the "Living Room". I've only restarted the iOS devices. Other than some simple troubleshooting, I am trying to understand why this has happened. My wi-fi has not changed. I suspect some sort of issue with the new iOS/tvOS of course. I may have to reset my whole Sonos system and start over (not a problem for me). Just looking for some input if anyone else has similar problems.