I'm having the exact same issue on a Roku Streaming Stick+. I have gone and authorized it about 15 times to no avail. Getting the same error you are. I even factory reset my Roku and started from scratch and same issue
Relogging in doesn't solve the issue. Rebooting my modem once a month is a ridiculous solution as that effects so many other devices and can often cause other issues. Xfinity needs to fix it, not require more from their customers.