There is a very old thread
here which asks the same questions and seems to come to the conclusion that what you want is not possible for the reasons that Sepiroth postulates.
In a related scenario I have a camera connected by home plugs i.e camera/homeplug ->-> homeplug/Wireless adapter (each floor is on a separate ring main) ->-> router which OK exzcept when you need to update the camera software when the second homeplug has to be connected directly to the router
So there are difficulties with homeplugs.