Roon works fine on a 4th Gen Apple TV connected to my Kef wireless speakers but not my other Apple TV. That is a 3rd gen Apple TV connected by optical to Vanatoo One speakers. Both are on the same network although the one that works is on Ethernet and the other is on wifi. Any ideas?
Verify that both are on the same subnet., i.e. 192.168.XXX.000, Where 192.168.XXX are the same for each.