I have been using powerline addapters for about a year and a half ana have had a great experience until recently. I have lived in 2 places and have had no problems then I moved back in with my parents who also use powerline adapters and after a month of being home I began to experience internet issues. The speed on the adapters had gone from being 20-40Mb/s on average with actual download speeds of around 3-5MB/s to <1Mb/s on average with actual download speeds being 80KB-120KB. When I plug any devices directly into the router the speeds return to normal (or better). I swapped out my powerline addapter set for my parents set and it was ok for a few hours then I experienced the same issues. I baught a new set of powerline adapters and everything has been fine for about 2 weeks and now im having the same problem. Iv tried plugging the adapters into various sockets around the house and tested on multiple devices.

I dont want to use a long ethernet cable because Im a student and I cant go drilling holes in any places I move into. It may be an option for my parents though. 

Has anyone got any advice as to why they keep breaking? 

Thanks.