The title probably isnt the most accurate, but I will describe my issue.
I run my 4TB MyCloud directly onto my gigabit wifi router. I then connect my OpenELEC box for my TV via 2.4GHz wifi. It generally runs quite well. However, when I run videos from the server via OpenELEC or even on my macbook, I get massive amounts of buffering (takes about 5-10 seconds worth every few mins) or it runs perfectly well. I have checked my wifi congestion, and the channel is quite empty. The general wifi works well. These videos are not bluray quality, but general videos.
I would hook the media box up with an Ethernet cable at least for testing. if it works well here it is a wifi issue which could be lots of different things