Ok first of all I have multiple AV500 / 2 x AV600 / 1 x Archer AX50

I have had AV500's working for a few years in all rooms in my house.  Recently the powerlines in my youngest son's room stopped working (AV500) followed by the AV600 in my bedroom.  I tried switching to new ethernet cables, new powerlines/extender, resetting, reconnecting and multiple different sockets.  I have got the one in my bedroom re-connected (all tests done in my sons room).  I can pair 2 devices downstairs but as soon as I plug it in, in my son's room the connection to the downstairs powerline (2nd light down from top) blinks.  The connection speed is anywhere between 300kbps - 600kbps (not a typo).  I have tried 4 different mains sockets and an extension lead all in my son's room.  I have an AV600 plugged in and fully connected to my hall socket which is, max, 5 meters away.

The only issue I can't rule out without a sparky coming is the sockets in his room but bare in mind this is 2 double sockets and a single socket on different walls, none work.

Halppp please :)

Wendy