The issue is that the lights "cycle," and there is no description of this issue anywhere I can find. The system has been in use for a couple years with zero issue until now.

Only one of the units has this issue. The Power light is always green upon plugging in. The Ethernet turns green, waits a moment, then the Powerline turns green. Then the Ethernet and Powerline turn off at the same time. Next, the Ethernet and Powerline flash once at the same time, the Ethernet green and Powerline yellow. The bottom two turn off, and the cycle starts over. Each stage lasts about 1-2 seconds.

The pair button on the offending unit does nothing. I can't do anything with the unit on the tpPLC application. I've swapped units around, and the problem unit stays the problem unit.

I tried the chat and got nowhere. I cannot believe that nobody has had this issue before. Has anybody else had this cycling/flashing light issue, and if so, what was the fix? I suspect it's a reboot loop issue but I have zero idea how to fix that when there's only one button and it doesn't do anything.

EDIT: After plugging and unplugging multiple times, and updating the firmware like the chat rep suggested, it is now apparently bricked. When plugged in, no lights come on and no amount of holding the button does anything. To say I'm angry is an understatement. Unless anyone has a suggestion, it looks like I'll be off to buy another powerline ethernet set. I'll be sure to go with something other than TP Link next time...