apple tv

I have 3 Apple TVs (2nd and 3rd generation) in my home. One of them is only 1 foot from my router and 2 feet from my Mac that runs the ITunes. It has a difficult time connecting to my itunes to stream a movie; it takes 5 minutes or more to start the movie, if at all. I run it with WiFi, but I have also tried connecting the device to my computer with an HDMI cable - same result. The other Apple TVs in my home (25 and 60 feet away) don't have a problem, maybe only 30 seconds to start a movie streaming. I have tried swapping the devices, but I get the same results. Any suggestions?