Orbi RBR750 doing odd DHCP things

I think it's fixed.

The system has been running without a glitch for several days now. What seemed to do it was:

1) Hard reset of the RBR750 by holding a pin in the hole for 20 seconds
2) Setting it up with a laptop plugged into the Orbi
3) Telling it to skip trying to set up satellites.

The satellites are working. The "Router" is working as a wireless access point. Whether they are aware of one another, I neither know nor care. The non-Orbi access points are fine. It is time to stop tinkering and take the win.

Thank you to everyone for your helpful suggestion.