I have an Xfinity XB7 modem/router with an AQ Vodka ethernet cable running to a Roon Nucleus Plus server and another Vodka running to a Nagra streamer. There are no other connections so I do not believe I need a network switch. The latter two have Tony Pardo linear power supplies and the modem has an xFi iPower Elite.
Again, anybody know how to access DNS settings?

