@ Weaver,I know these adapters give out a lot of 'mush' but there is no DSL or ADSL, VDSL etc to affect, I think the building is lined with silver backed plasterboard, part brick part timber frame.
@ d2d4j
re 'I am not sure what you mean by heavy duty Ethernet sorry'
It looks like SWA Ethernet cable, it comes straight out of the ground in through a hole in the window frame, about 6mm Dia, Black, looks like Cat 5 that is plugged into the Access point.
I have a feeling it is just a router used as an WiFi access point, She is sending a photo of it tomorrow,
If so I will just plug one of these mains extenders into the spare Ethernet sockets on the back.
I think I have said to you before the the Ethernet is controlled by the firm, eg passwords and access codes, But If she had one of these mains WiFi repeaters could I set up her own password for it ?.