There is a 6-port switch in the rack that connects all of the components.
The prior owner seems to have taken the main network switch, so I installed an unmanaged 24-port gigabit switch. I also replaced the cable modem (since the provider, Shaw Cable, would not reactive the old one) and I added a new Deco mesh wifi network.
I can see the Apple TV and the Lurton controller on the network and there were a few other “unknown” devices that also joined then I connected the switch in the C4 rack, so I assume that’s the C4 box and the other components, but haven’t explored it any further yet. Also, the C4 remotes no longer complain there is no net work, they did before I added the switch.