There are lots of people on the forum using the Xfinity router successfully, so I don’t know if that’s the problem. The exact message might tell us something.
My Roon Nucleus would not work with the USB A out to USB B in on my Denafrips PontusII DAC, so I contacted AV Specialists in Tucson. After 2 hours we discovered that using an HDMI out from the nucleus through a Tech Digital converter, which converts digital to Toslink and it worked! I’m a happy guy!