How can I find the bottleneck in my media server setup? On seemingly random occasions, streaming media from iTunes on a Mac mini to my Apple TV (3rd gen, latest software) will result in slow buffering of movies. The catch? There's no consistency to when it happens, and I don't know how to diagnose it when it does.

I've tried restarting the Mac, wireless box and Apple TV at that point, and it almost never makes any difference (as in, it stays pretty slow). When it's working fine, movies start playing inside of twenty seconds and don't pause to buffer at any point. Since I know the Apple TV is capable of streaming and playing back these sorts of files without issue, so I suspect a network issue, but I have no way to verify that.

My main suspicion, due to the seemingly random nature of the problem, would be slow wifi speeds. Here's where I get annoyed. Older versions of the airport utility had a panel where you could see the speed at which devices were talking to the base station. In 6.0 up, it's not there any more. In any case, I've tried playing with wireless channels, but it doesn't make any discernible difference. The settings screen of the Apple TV indicates 4-5 signal bars whenever I check, but I have no idea how reliable that is or what it actually means. Is there any way to see this info?

I'd happily get some powerline ethernet adaptors, but I don't want to waste my time if the wireless speeds I'm getting are fine and the problem is elsewhere! Any pointers would be much appreciated.

Extra (but possibly irrelevant) details:

The files in question are almost always 10GB+ 1080p files, all ripped and remuxed the same way. They're stored on a 4-drive RAID enclosure connected by FireWire 800.

The network is an 802.11ac AirPort Extreme that's in charge of everything — DHCP, etc etc. The Mac mini is connected to the Extreme via Ethernet directly (no switches), and the Apple TV is connected via wi-fi.
It could be


other wireless devices on your network using wireless bandwidth
a wireless device connecting at a speed that is forcing other connections to a lower-speed protocol
wireless devices not on your network but using an interfering channel
another process on the Mac Mini using network bandwidth


Signal strength and signal quality do not always go hand in hand. Think about somebody shouting in a tunnel—the volume is there, but the clarity will be drowned out by an echo.

One test would be to set up a new SSID and password and connect only the Apple TV and your streaming computer to it (temporarily) and see how that goes.