I have the same problem for the past few days. Image quality is so poor that it is practically unwatchable. I have 75MB cable broadband & can watch Amazon, Netflix, BBC iPlayer, 4OD etc. with no problems whatsoever. Watching on NowTV black box.
I get the same issue. I am with Virgin 50Mb fibre and all devices show a normal full download speed. I made a guest account to try and resolve this issue but it only works for 30 min and it's back to a very bad quality picture!!!
I didn't have this problem before the last update so it may be connected with that I guess.
DO SOMETHING NOW TV !!!!
Same problem with pixelated / buffering issues over the last two days with my new smart now tv box thats hardwired to the router.
its not the internet as netflix works fine, the older now tv box works fine and now tv works on my apple tv box.
but the buffering and the picture breaking up makes it unwatchable,