I'm using two Deco X55 units connected using Ethernet backhaul. The satellite is showing as offline in the app, even though I can access the Internet through it via Ethernet.

I've been emailing TP-Link support back and forth for weeks but they haven't been any help and seem to just copy and paste from scripts (I've lost count of the number of times they've told me to reboot/reset things). I guess they've run out of ideas now because they're asking me to RMA the units. The thing is, I've already replaced the satellite once with a spare (there were three units in the box) and it only "fixed" the issue temporarily, so I have no confidence that replacing all of them will solve anything.

Does anybody else have any idea what the problem is or how to go about diagnosing the actual underlying cause?