This is an excellent question! As long as both Powerline adapters are on the same circuit in your home, you shouldn't have any issues. Generally, these adapters will have a "link" light on them. As long as this is solid, you know they are communicating with each other. Here is an article that provides some general information on these adapters. What to do if your router is not near your Slingbox. I hope this helps!
Sling Moderation Team