Thank you for sharing your experience @AdamW! The intended operation of the Alarm’s battery backup is to operate as efficiently as possible while preserving power in an attempt to help you obtain as much of the 24 hours of battery backup as possible.
This means that when battery backup is initiated your Base Station will remain connected to wifi if your home network is still available, for up to 15 minutes. It will then automatically switch to cellular backup connection and reserve it’s functionality to only monitoring sensors, emergency signals, and arming/ disarming features. This is, of course, to preserve battery life. I hope this helps! 