Phone loses service after disconnecting from wifi.

When I leave my home and my phone disconnects from my home wifi (also xfinity) my phone loses all cell service. The only way to fix it is to switch airplane mode on and off. I have let it sit while I drive to see if its just being slow and it never comes back on its own. It also does this when I leave my friends house who also has xfinity internet. When I visit my sister who has a different internet provider everything works perfectly when I leave.