After swapping to different outlets in the same room, conclusion was that since this room has a coal fire, perhaps the sockets themselves were to blame since all 3 of them are slow (maybe some soot...

Thanks, I did already do some swapping around but I need to be more systematic this time. Will have a play around and see where the issue lies, whether it's a specific socket or what.

Model : TL-PA7020 KIT (UK) Hardware Version : 1.0 Firmware Version : 3.2.0_702011_151203_006 ISP : Plusnet (BT Wholesale) Recently purchased 2 kits (4 adapters) so that I could move my Sky Q box...