I have the following setup...
iTunes home sharing from a x64 Windows computer (Server 2008 r2)
2 Apple TV (3rd gen)
iPhones (4 and 4s)
Ipads (1 and 3 gen)
Airport extreme router
My problem was that every now and then my clients were unable to connect to my home share. I could see the home share but when I tried to connect, the progress "pie" stopped at about 50%. This happend a few times a day and always in the morning the home share was not responding. This happens regardless client (windows, mac os, ios)
I have been trouble-shooting this for weeks, tried everything but nothing made any difference, the next day home sharing could not connect! But now I have found a solution that at least works for me!!
There is definitely a problem with the ATV and how it handles network connections.... But I have found a workaround!
I used a tool (TCPView) to sniff all open network connections against itunes.exe on my host computer, and found that my ATV connections did not close correctly, they just piled until I had about 50-100 open network connections. Then home sharing stops responding! Probably because itunes had reached max number of connections. I tried to manually close all open client connections, and home sharing came direct back!
I had one ATV hard wired (ethernet) and one wireless. I decided to trie and put both ATV's wireless, and what do you know! Now all connections get closed correctly and itunes home sharing has for the first time worked over 24 hours!!!
My sharing computer (windows) are still hard wired (ethernet) with both IPv4 and IPv6 enabled.
Hope this experience can help someone else!