Powerline Adapters
I had similar trouble with mine not pairing up unfortunately although they were okay in the house ring main circuits they would not work as far as my Garage - must be a combination of the distance from the house. Also I have a Consumer Unit in my Garage just too much resistance I guess.
I ended up hard wiring an Internet cable from house to garage as the Wifi will not give a good enough signal.
I used an old telephone conduit from house to garage put in by VM when i had a hard wired telephone out there in the days of dial up internet.lol
Another thing I found was that I could pair up the Powerline Adapters when they were next to each other in a socket then when done put the output one where I wanted it - saved a lot of time dashing between rooms and holding down buttons etc.