Hi again., below the results of my tests; UK Double socket(MK), TL-PA4020P capable of 500Mbps one each plugged into the double outlet, throughput measured at 366Mbps, same socket! Same Ring,...

I'm not Powerline Support but I have a similar property (3 floors). Router on ground floor, 2 upper floors on separate fuses. Powerline connectivity is possible to separate rings, through the fuse...