Xfinity stream app

Have a brand new firestick and the Xfinity stream app is not working properly. Sound just drops out. Mostly on CNN and MSNOW. I have tried everything. Uninstall, sign out clear data and cache. Restart modem, Turned off feature that lets Xfinity pick best channel. Turned it back on. Every suggestion I have seen in forums. Nothing has resolved this issue. Old firestick seemed to work with stream app okay. Have another in my room. Please help.