My doorbell2 drops connection to Xfinity Wifi Gateway router

I got my ring doorbell2 in December and so far my experience has not been good. Besides its battery issue (last about 3 weeks after a charge, reported to Ring already), the doorbell keeps dropping connection to my Wifi router. After each setup (it is a pain to open the cover each time in the middle of winter), the connection can last from somewhere 2-3 days to a week. I have configured my router to assign a static IP to the doorbell and drop firewall setting to the lower level. But the doorbell is still disconnected after a while. I have Xfinity internet at home with its Wifi Gateway router. Anyone experiences the same and knows how to resolve the issue? Thanks,