I’m having the same issue. I know my internet is still working because, eg, streaming boxes will continue playing, but my Apple devices (iPhone 11 Max, MacBook Pro and iPad Pro) all hang. If i open the Xfi app, it is usually very slow to open during a hang but finally opens and says the internet is fine, then magically my devices are connected again.
For solutions, I’ve read to log into the modem and change the channel from automatic to channel 11, and/or create separate names for the 2.4 and 5.0 gHz networks (but that solution is incompatible with Xfi Pods, which i have).
Good luck! I’m about to set up my trusty old Google Wifi Pods and put that Xfi gateway in bridge mode. It’s maddening to have no internet every few minutes.