Home App on IPhone

Ever since I switched my phone service from Verizon to Xfinity and made some changes to my services, my app works “sometimes” when I open the app there are 3 dots and says now connecting to your home. But does not connect. Other times it dies just fine. I have reinstalled app, checked WiFi connection, restarted phone and it doesn’t correct it. This is very frustrating because I depend on the app to monitor, arm & disarm. Which I cannot!!!!! Please help