RBS20 - disconnects when connecting ethernet backhaul

So last week i pulled out my linksys velop mesh after finding that, for some reason that neither myself or linksys support could determine, i was only getting about 30% of my ISP speed even on wired connections behind the velop. 

I had put an RBK40 system in my mother in law's house some time ago and found that they weren't using it, so i took it back home and connected the RBR40 router and one RBS20 in my home using my wired ethernet to create a wired backhaul between the two. Works great, i get 700-800mbps on my wired (ISP delivers 1gbps) and 400 or so wireless. Could be better, but this is fine until i upgrade to something wifi 6. 

Now here's my issue: i have another RBS20 that I have added, and using the 5ghz band as the backhaul connection type, there's no issue. However, as soon as i connect this RBS20 to my wired network, my whole network loses internet connectivity. 

I have some more testing i need to do when my wife and kid don't need the network for work/school, such as determining if all wired and wireless connections go down when this happens or only devices connected to this specific satellite. Just wanted to see if anyone had seen anything similar before I go down this rabbit hole.

RBR40 2.6.1.36

RBS20 (2) 2.6.1.38