Orbi RBR850 / RBS850 – Constant IoT disconnects (Shelly, robot vacuum, etc.)

Today I factory reset it all, inserting a pin into the reset hole. I have left only the RBR online.

Exactly the same thing is happening, my devices are flipping between connected/unavailable.

I should not that they are on the IoT network, which is 2.4GHz only.

Computers/phones are working fine.

Now try turning on ONE RBS. 30 feet out from the RBR.

This seems to have helped, but can you explain why? Both my devices are closer to the RBR than the RBS.
In Home Assistant, it is still reporting flapping for my robot, but not my shelly. I think it might be just short interruptions though (unavailable for exactly 1 min each time).

https://imgur.com/a/7M84t5Q

Edit: My shelly had a fallout for about 4 minutes today.
So its improved a lot (no idea why), but not completely stable.

So just one RBS online currently and the power on the RBR set for 100% or 50%? 

What channels are you using on the RBR currently? 

Seems that these devices may not handle working with MESH systems with multiple signal sources, seems like they maybe ping ponging back and forth trying to keep connected to one. Something you may wanna contact the Mfr about and how they are handling and connecting with MESH systems. I ran into this years ago with NEST controllers. 

The reason that Im asking is, that when I initially set this up, it was working great for months. Until suddenly they started dropping constantly.

Correct, I have only one RBS online atm.

I dont see an option to change power for single unit, just change it for 2.4 or 5 GHz.
After factory reset, it is now back to 100% for both.

The power change seen on the RBR is for the entire system, both RBR and RBS. Can try 50% with the RBR and RBS to see if anything changes. 

Possible some changes at the SW/FW level on those devices as well on how they handle wifi signals.