I just purchased a set of these to attempt to bridge floors in an old house that would require extensive work to run ethernet between floors. Built 1897. 

I plugged 1 into an outlet next to the junction box that feeds the 3rd floor. The link there read ~500Mbps in the TP Link utility app and speedtested through at ~ 100 Mbps. The WAN link is 1G fiber that the router sees ~900M symmetric. I saw mention of motors and compressors and the plug I used also has 2 refrigerators in it so I tried moving it to the other side of the house. There I see a line link ~220M but speedtest through at 30M down, 50M up. I have disabled power-saving since their purpose is a full-time bridge to connect the 2nd floor to the basement and I set the QoS selector to Internet.

I can get 400M using APs to wirelessly bridge and was hoping for something more stable and faster throughput.

To get a 2G link, do these things need to be connected to a double-F extension cord? What factors affect the link speed and throughput?

I saw mention of this being a reasonable bridging option on the Unifi forums but I think they might be crazy -or have all new wiring. The wiring in the house is not as old as the house as there is no evidence of kn0b & tube anywhere in it.

Any suggestions for improving this before I revert to the WiFi option and return these?

Thanks