I have a similar issue with my RBR850 but I'm on V7.2.6.21

I'll try the 30-30-30 and report back.

Tks for the tip about other RBS' compatible with the 850 but if the reset you outlined doesn't work then I've gone past my limit time wise.  Whats crazy is 

this is my third Orbi and if I replace it with another Orbi then I think I lost my marbles.  Always the same thing, some error and too difficult to find the root cause but replacing it 

works for a few years.