Orbi RBR50 keeps going offline. Need to press sync button to get back online.

Has a factory reset and setup from scratch been performed since last FW update? 

What is the size of your home? Sq Ft?
What is the distance between the router and satellite(s)? 30 feet or more is recommended in between RBR and RBS to begin with depending upon building materials when wirelessly connected.
https://kb.netgear.com/31029/Where-should-I-place-my-Orbi-satellite