My new Samsung TV 65" Q70 continues to display blank screen when trying to use Xfinity Stream App

this has been going on for the 3 months i have owned the tv.  I have called Comcast support at least 6 times.  It will work for a couple of days and then the blank screen again.  I have even called Samsung 3 times but the same thing happens.  The other apps (netflix, prime video, you tube) all work flawlessly. the procedure comcast puts me through is unplug the tv, uninstall the app, reinstall the app but again, it works for a day or two and then goes blank.  Over the course of the 3 months, i sometimes receive 2 error codes:  TVAPP 00100 or "we're having problems reaching the configuration server. Please check your network connection and try again".  It is not the internet connection. All my other devices are working on the server. Please help!