After a recent software update (I think) I can no longer stream video from iTunes on my my iMac to my ATV 4K. I think this may be something to do with airplay 2. I am connecting over ethernet which used to work fine. Have restarted everything multiple times - problem has been going on for weeks now. When I try and select "Living Room' (my ATV) in the iTunes airplay menu, I get the message "Could not connect to Living Room" and then "The AirPlay device “Living Room” cannot be selected for audio output. Please verify your network settings and AirPlay configuration or select another device." Strangely I can stream video to the ATV using Airplay Display (in System Preferences > Displays) - so everything is clearly connected - just can't stream from iTunes. Does anyone have any idea what the problem might be and how to fix it please? thanks.