Hi,

I have 3 TL-PA717 AV1000 powerline adapters, but I'm having trouble with one of the adapters which was previously working. 

The first adapter is plugged into a socket next to my router, connected with an Ethernet cable from the router to the adapter - all 3 lights are showing.

The second is in one of the upstairs bedrooms which is working - all 3 lights are showing.

The thired is in anoher upstairs bedroom which is powered and paired, but when I connect an Ethernet cable from the adapter to the device, the third light is still off. 

I've tried re-pairing the adapters, I've tried using a different Ethernet cable, I've tried moving the adapter to a downstairs socket closer to the first adapter. I've also tried the second adapter in the same socket with the same Ethernet cable and that is working. However, with the same setup I've had for years, I can't get the adapter to show the Ethernet connected light, and therefore cannot connect the device.

How should I go about troubleshooting before I purchase another?