We’ve got Powerline adaptor, TP Link AV500 ones. 1 wired to the router, 4 wireless ones around the house because it’s all brick built and seemingly impenetrable to WI-FI unless you’re in the study!
Seem to work well enough, although can be slow to move from one point to another so sometimes I walk into the kitchen and there’s no wi-fi despite being stood next to the plug.
Haven’t noticed any interference issues.
There was something about the number of access points and users and max speed they could then achieve, but it’s 500mbs divided by whatever, so it would need a lot before it actually impinged on the speed of the broadband itself.