Roku’s response sounds correct to me. Ie: it’s Xfinity’s app, using whatever method they use, to complain that you’re not on Xfinity’s network. I don’t see how anyone but Xfinity can control that.
Searching around, I see Xfinity users getting this message on various devices. (Not just Rokus, but Smart TVs, phones, etc.) I assume you’ve done an: uninstall the app, reboot the roku (don’t skip this), reinstall the app cycle?
Most of the threads I found just end with no explanation of whether or how it was fixed. A few threads have some interesting clues, like some people with multiple homes, or people logging into the wrong network (ie: Xfinity’s hotspots) apparently even connecting to a Wi-Fi extender might cause issues.
In one thread, the first post says that Xfinity told him it is not their problem, and the next post said Xfinity told him it was a known outage!
I would suggest starting a thread on Xfinity’s forum.
