Unless you're on an AFCI circuit or split circuits in your house. Or have old wiring.

I tried one in my old place and it was really poor - much worse than congested WiFi (dense neighborhood in a large apartment building).

It can work. I installed one in my dad's old house and it worked like a charm. But when I went to put one in my house a few months ago, I did get it to work, but I had to try various locations of ethernet jacks and power plugs to find a combination that both worked and usefully extended my WiFi.

According to the incredibly comprehensive "understand Wi-Fi" guide posted here recently, MoCA is likely to be better than powerline adapters.[0]

[0]https://www.duckware.com/tech/wifi-in-the-us.html#improvespe...