I'm not trying to hijack this thread, but I'm having a similar issue with users being dropped at random times. It also seems that once it happens to one, it happens to at least a few of them on the same cluster, but connected to different AP's. We also have the IAP-225, but we have 61 in our cluster. When I'm looking at the virtual controller, I'm not seeing anything wrong when the users are reporting outages. I will sometimes get alerts that a DHCP request has timed out and occasionally a RADIUS timeout, but that's fairly typical throughout the day and not limited to when users are experiencing issues (and it's typically not reporting an issue for those clients who have contacted me). Over the 61 AP's, we're typically running in the range of 300-350 clients, the vast majority are Windows, but there are more than a handful of phones/tablets. We're broadcasting out 3 networks, our secured network and 2 guests. The clients we get reports from are on the secured network, but then most of them are connected to that network (I'd say 90% of them).
I did try the suggestion to turn off 80Mhz channels and Enabling Broadcast Filtering, but it doesn't seem to be helping. I'm willing to post my config if you think it's a setting.
Thanks for any assistance!