To my knowledge, Netflix does not provide Dolby Digital 5.1 surround on any of their streamed content. There is nothing wrong with your Apple TV, but until they change something on their end, you will only get 2 channel stereo from Netflix, as that is the only audio signal they stream. I have had a Roku HD player, and a Samsung Blu-ray player that both streamed Netflix, and both would just be stereo soundtracks. If you have a surround sound receiver, use the Dolby Pro-logic II Movie mode, and that will expand the stereo signal into 5.1 surround. It's not quite as good as true discrete Dolby Digital, but does a pretty darn good job. I use this on all Netflix streamed movies.