Alex,
Not sure if this is your issue, but I had a similar issue months ago and we suspected a wireless AP / controller issue. It turned out that wasn't the problem. It was an issue originating on the wire.
We had a single Lenovo PC with an i216/i217/i218 (not sure of the exact model) Intel NIC that was causing 100% of the issues. Here's a link to the problem:
https://communities.intel.com/thread/48051 But in short the Lenovo PC NIC / NIC drivers were sending IPv6 multicast traffic to ever port on the network. This only happened when the PC entered a sleep state, so it wasn't consistent. We would be fine for an hour or two and then we'd be down for 30 minutes to 4 hours.
The wireless symptom was that wireless clients would drop and an occasionally the AP's would drop and come back up. The reason for that was that the AP's (7982's) were so busy processing multicast traffic that it couldn't service the wireless clients and if it was bad enough it didn't have time to make the heartbeat timeout with the controller so they used their controller based settings that are pushed to them, to reboot after 30 minutes of no connectivity with the controller.
Once we found the device mac using wireshark, we were able to narrow down the port the PC was plugged into and removed it from the network. Problem solved.
Good luck with your issues.
