I heard that those ones need to be on the same power network though. Modern homes, like this 2 story one for instance, would have at least 4 power networks. Best thing is a wifi modem and good router on the next level.
Ask a builder, most houses are single network for the power points. Some really large houses might not be, but ive lived in a normal sized 2 storey which worked fine upstairs to downstairs.
It shouldnt affect the equipment like the router, power doesnt travel from the point through the lan cable to the router or pc. I was sceptical about them for years, thinking they would blow up my equipment. Then i lived in a house that hated wifi, and the cost of putting points everywhere was high. Also the missus wouldnt want cables running everywhere outside the walls. So i tried them. They are cheap to impliment. Never looked back.
Never had any equipment blow up, or problems with connection. Maybe once every few months on average i have to turn them off and back on when they lock up. I guess things that could change that are shitty cheap powerline adapters or poor house wiring (if thats the case internet isnt you biggestr concern). Compatibility issues i havent heard of (doesnt mean they dont exist, i havent had to look into it). The signal is filtered by the adapter and only a normal lan signal goes from the adapter to the equipment. Id say the equipment was the issue for people who had that.
Just a cheap option that works well for a lot of people. About $50 per point (and you need one at the router too). Ive even tried them in a house that was 40 years old and 2 storey, no issue.