As said they can't seem to find each other despite being on the same powerline. I got them to connect to each other once but it required plugging in a wireless adapter to connect to my wireless network. I've checked to see if it is connected to the correct network and it has an address starting with 192.168. Any ideas are appreciated.
Try disconnecting the Ethernet cable to the computer and the adapter then placing the that adapter in a wall plug next to the one connected to the Router and then pair them up, when paired (you will see by the lights) move the slave back to the computer.