Problem with Xfinity stream app

I used to be able to stream on my phone with the app. About a month ago, I no longer can. I receive the connection error TVAPP- 00251. I can’t find any info on it. I have deleted and reloaded the app several times, verified my local phone settings, turned the phone off and on several times. I’ve gone through troubleshooting with Xfinity and still can’t get it to work. Any suggestions?