ORBI RBKE963 randomly disconnects from Internet

I have the same Orbi RBKE963 + extra AXE satellite connected to the Xfinity XB7 gateway (not the latest, which is XB8 and gradual rollout) in bridge mode.  I do not experience the daily disconnect problems you are reporting, so let's check if there are any differences.

1. Exactly which gateway do you have?  Pictures are here: https://www.xfinity.com/support/articles/broadband-gateways-userguides.  The XB7 has a slightly different top holes pattern than the XB8,
2. How is your Orbi router connected to the gateway?  Is there a switch or anything else in between?
3. Have you tried swapping the network cable from Orbi to gateway (just in case)?
4. What do you do to fix the Orbi connectivity when the disconnect occurs?  Do you go to orbilogin.com and press a Connect button and it recovers immediately?  Describing your recovery procedure may help to isolate the nature of the issue.
5. As per the other reply, try switching to AP mode after taking your gateway out of bridge mode.
6. You may have an Orbi hardware problem, you can request exchange under warranty (longer than tech support 90 days).