Since it took me a while to sort out some connectivity issues I was having with our Orbi system, I wanted to share my resolution here. This post ( https://community.netgear.com/t5/Orbi-Wi-Fi-5-AC-and-Orbi-with/Orbi-ethernet-backhaul-issues/m-p/16... ) and the discussion in that thread is what really led me to double check the ethernet cables I was using to connect my Orbi satellite and my Orbi router. Once I re-checked the cable with a tester (it's a simple one, like this: https://www.amazon.com/Network-Tester-Continuity-Twisted-Connections/dp/B08JQ6J6XZ ) I found that it was not good. I have an internal issue in the cable somewhere, as even after double-checking the wire colors to the pinouts and installing new connectors, the cable still tested bad. Once a good-tested cable was used, all my internet and wifi connectivity issues resolved.
I was really at a loss trying to figure this out, until I resolved the LAN cable issue. Any device on the network (wired or wifi) would wind up connecting and disconnecting from the internet. From the linked thread and others, it seems that if the wired backhaul to one of the satellites is not good, it can wreak havoc across the whole Orbi system (not just for devices that connect the the satellite with the bad connection). Fixing the bad backhaul connection stabilized the whole Orbi network. As long as my connection to the ISP is stable (that's been a whole other issue lately where I live), the internet connection of our devices has been solid since the backhaul was fixed. Hopefully this insight can help others.
For background, the topology of my network is: Spectrum cable modem connected to the Orbi router, and then a Ubiquity ethernet bridge links to an outbuilding with one of the Orbi satellites, and the other Orbi satellite is located on the other side of the house using the wireless backhaul, for now (I have yet to get more CAT6 cable to fashion a new wired backhaul connection across the whole length of the basement).
