Hi @Jack_O_Donoghue,
After restoring a Backup, updating Roon/RoonServer, or updating MacOS, have you re-verified that Local Network permissions are toggled on for RoonServer in System Settings → Privacy & Security → Local Network?
MacOS Sequoia (15.x) has more secure network permissions. This causes Zones to sometimes lose access to RAATServer via the loopback interface. We have a ticket open to investigate this behavior. In the meantime, try re-toggling Local network access anytime you restart RoonServer.