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Intermittent problems are often a result of interference. Interference can be caused by other networks in the neighbourhood or from household electrical items.
You can download and install iStumbler (NetStumbler for windows users) to help you see which channels are used by neighbouring networks so that you can avoid them, but iStumbler will not see household items.
Refer to your router manual for instructions on changing your wifi channel or adjusting your multicast rate.
There are other types of problems that can affect networks, but this is by far the most common, hence worth mentioning first.
Today I ran into the same issue. I installed my new ATV3 and started watching videos in my home share. After a few minutes the video stopped and ATV did not recognize the existing & activated share. I had to restart iTunes again to watch for another 5 minutes. Disabling the Windows firewall indeed did the job, but that cannot be the solution. You should not need to disable security features. I double checked that itunes is in the list of allowed programs in my firewall settings, but that's not enough. Interestingly, if I "push" the video from iTunes to my ATV there is no issue (at least not after about 25 minutes). However, if I "request" the video from the ATV, the video stops after a few minutes and the home share is lost until I restart iTunes. I have not yet tried to explicitly open the ports mentioned somewhere on the Apple site. Maybe I'll try tomorrow...
I was too annoyed to wait until tomorrow and tested the following: despite iTunes already being in the exception list in my Windows firewall settings, I opened TCP 3689, UDP 5353, and UDP 123. Instead of 5 minutes video I could watch more than 40 minutes without interruption. I'm not sure yet whether or not you need to open all ports or only one of them. I will do more testing tomorrow, but hope that fixes the issue.
I haven't posted to these boards for a long time, but I fixed my ATV3 HomeShare dropout issue (e.g. ~5 min of streaming then booted to menu). I have all the latest updates for all my Macs & iOS devices; I also use an Airport Extreme. The solution for me: go into Airport Utilities and deselect "create hidden network," as soon as the airport reboots, your good to go.
Just my $E-2
Message was edited by: danhz
It's not the Windows firewall, it's the new iTunes - trust me. Your stuff will only work for a day or so before you have to restart iTunes or disable / enable home sharing in iTunes.
Home sharing with the new Apple TV / iTunes update is just broke. Only works for a bit unless you restart iTunes or disable / re-enable Home Sharing. Use to work great until the last updates. This is not a network (router, firewall, ...) issue - just a (bad) regression in Apples software. Hopefully they fix this soon, hard to believe its been broke this long already. The Remote app update also fails to connect to Apple TVs (but does connect to iTunes) for many people as well. Poor QA all around. :(
I have yet to see any suggestion that actually works other than reverting to previous versions of fwr / iTunes - which is a pain / joke to do.
There are a *ton* of posts about this: