If you don’t want to play music that is stored on the Roon Server, i.e., just downloads on the phone or streaming, then the Roon Server apparently doesn’t have to be running. But you need occasional internet on the phone:
If you don’t want to play music that is stored on the Roon Server, i.e., just downloads on the phone or streaming, then the Roon Server apparently doesn’t have to be running. But you need occasional internet on the phone: