RBK853 Ethernet Backhaul Causing Wifi to Drop

Orbi RBR850 in office connected to the modem.

RBS850 in kitchen connected wireless to the router.

RBS850 in basement connected via an unmanaged switch that has an ethernet connection directly from the router.

All updated firmware: V3.2.16.6

(When connected by ethernet backhaul, both sats are getting signal from the router. If I do not use ethernet backhaul, the kitchen sat connects to the router and the basement sat connects to the kitchen sat.)

When I set up my system without ethernet backhaul, it works great. I have gigabit service that is business class and very stable. So the modem and connection are not an issue. I get over 900 Mbps 5 ft from the router. Most of the house is around 500 Mbps.

I would greatly prefer to use ethernet backhaul in the basement as above. It increases my speeds in the basement by a good margin. It also seems to increase speeds from the kitchen satellite. I know, dedicated 5 GHz wifi backhaul, but my speeds definitely improve when the basement sat uses ethernet.

So I am getting intermittant extraordinarily frustrating issues when I use ethernet backhaul. It will work perfectly for a time (10 minutes or 10 hours), then suddenly internet connection will drop completely - still a wifi signal, but no internet access. I know internet is still active because TVs streaming from ethernet connection from the switch do not lose any connection. I can diconnect from wifi using any device and then reconnect, and internet will return, only for the cycle to repeat.

Today, after being stable for over 12 hours, the entire wifi network lost internet connectivity. 

The solution? If I simply unplug the ethernet cable from the basement sat, internet connection returns almost immediately. 

So ethernet backhaul seems broken for me. I gave it a lot of time to "stabilize" or "optimize", but it makes no difference. 

Is there a solution to this issue, or perhaps a setting that can resolve this?