I have had issues with ARC from day 1 off and on. I have a similar setup as Charles here but my deco mesh routers in ap mode are after the xfinity router. I have port forwarding and upnp both enabled/setup on the xfinity router. For months it’s been hit or miss if ARC worked, some days it would fine others no. Last week arc worked all week and now I’m getting error 502. What gives? Why the inconsistency? Do I need to port forward on all routers and/or enable upnp on the deco routers too?
The only thing that changed lately is that I rebooted the roon server. This server is connected to the deco router using an Ethernet cable.