I'm going to hijack a post from Grandude, posted February 25, 2014, because it is an excellent narrative of one of the nuances of using Powerline adapters. My neighbor has Comcast service, and runs it to a Tivo Roamio Plus. He has the problem of three-story townhouse, cathedral ceilings, inaccessible subfloors, so he needs a way to make his Moca work without the wiring runs, as he is trying to set up TIvo's version of a Joey, i.e., a Mini. He contacted Tivo Support and was told with resolute certainty that the Powerline system will not work for the Tivo units. Now, maybe they were just covering their rear ends, like DISH does on certain workarounds that are not in their book, but still work.
Grandude speaks:
"You probably should test all the locations in your house that you may want to use as you may find some that don't work and some that will.
Depends on which side of the power each location is connected in your circuit breaker box.
Typical power to the house is 250VAC and is split in the CB box roughly in half with each side paired to neutral with only the neutral in common. If the line you want to use is on the other half of the power line you may have trouble using powerline ethernet connection.
Give it a try before you need it. I had to run a dedicated ethernet line to a location from my PC/router setup to the garage to get a solid signal for a specific application. (That was a bitch of a job as it was opposite corners of the house and being on a slab, had to go through the attic. No fun at all.)"