Recently, I saw an issue with AppleTVs disconnecting from our Cisco Wireless Network. No matter what we did, the AppleTV would just lose its IP Address and Wireless Signal. This was actually happening at two separate location- both had a Cisco Wireless Controller. After about 60 seconds – the AppleTV would connect again. Then, after a very short amount of time, it would disconnect again.
The AppleTV would work just fine with a wired connection and it worked using an old Airport Extreme Basestation.
The Apple TVs were tripping the IP Theft or IP Reuse Client Exclusion Policy on the Cisco Wireless Controller. If you have access to your wireless controller – you can search the “Most Recent Traps” section for excluded clients. This fix will only work if you see the mac addresses for your AppleTVs in this log and it should say excluded next to it.
All of our Apple TVs were being excluded for some reason due to that policy. There was also a rule that would unexclude after 60 seconds – which is why the AppleTV wireless connection would work and then disconnect.
Unchecking the IP Theft or IP Reuse setting under Security -> Wireless Protection Policies -> Client Exclusion Policies has solved this issue for us.