[Luke M]

I am disappointed with wireless performance of the stick though - average of 110mbps will probably not be enough to stream 100Gb UHD material, especially since the speed fluctuates a lot depending on other devices using wifi, so even if I solve my powerline problems I might need to have stick wired anyway... 

 Have you tried playing high bitrate content from local storage? If it can't do that (likely!), then you don't need to worry about networking performance...