RBR50 fails when connecting satellite via EoP

I’m trying to connect my router and satellite via a Netgear Powerline 1100. The connection works great when wireless, but when I plug in the Ethernet connection, the entire system goes down. Devices remain connected to the router, but the external internet connection drops. I followed the instructions in this document, bI’ll keeping the external Ethernet connection in the yellow jack: https://kb.netgear.com/000051205/What-is-Ethernet-backhaul-and-how-do-I-set-it-up-on-my-Orbi-WiFi-System

 Both router and satellite are on the latest firmware version, 2.0.1.4.

I feel like I’m missing something stupid, but the setup is so easy that I can’t figure out what I could be doing wrong.

Does anyone have any guesses where to look?

(For what it’s worth, I’m getting such good performance from the wireless backhaul that I’m not even sure the ethermet connection will be an improvement. But I‘d still like to get it working to find out!)

Thanks for any ideas.