powerline ethernet 85 adapter won't connect

I have 2 powerline ethernet 85 home plugs that aren't currently connecting to each other. They have worked before.
Internet is working, signal is going from the router to the first homeplug with all green lights on. Wherever i plug in the second adapter the lights remain on red. I have switched them round and connected them both on the same plug socket.
I have reset the router
Nothing I do can make them communicate with each other. I would welcome all suggestions