Hi
Hard to pinpoint the problem, without more info.
How about listing the controller, AP type, and running software version as well.
I have seen a few problem regarding AP-225, but as i don't know your setup i can't say.
At the same time, find a client with the problem and add a user-debug towards the client.
#logging level debugging user-debug <mac>
This might point you in the right direction of the problem.
Roar Fossen