Leo, I did not see a new thread created so I am going to answer on this one really quick. (Sorry)
I did not get an exact answer, but enough to figure out what was happening. The issue arises between the WLC and DHCP lease times. In my situation, the DHCP server (which is not controlled by me) hands out 8 day lease times. On the WLC there is an "Enable Session Timeout" under each SSID in the advanced tab. If the timeout is set to be less than what the user is on the wireless, for example time out 4 hours, user in office 9 hours, the user will be forced to re-authenticate every 4 hours. The problem is that the client machine has an 8 day lease on it, and the WLC is looking for the DHCP request which it does not get since the machine still has a valid lease, hence it gets stuck in DHCP required state. To fix this issue, you can disable the "DHCP required" under advanced tab, or match your timeout to DHCP lease time, forcing it to get a new address once it re-authenticates. For example 9 hour timeout (typical user day 8 hours plus 1 hour lunch) and 9 hour DHCP lease. You would need to do some testing to make sure your timing / DHCP lease match works properly. In my case I had to disable it because our LAN group does not want to budge on lease times. Let me know if this helps. Also if needed please create a separate thread or just select this as the "correct answer" if it works for you.
