so it doest even get an ip address?
The dhcp you using seems to be on the Wireless controller
If it that way how many users do you have using the DHCP Server?
What is the firmware you got?
You know that since the version 6.1.3.x the limit of the DHCP leases is 512...
The thing is that when you go over that strange things can happen... its on the release note... as aruba saw this was happening i think, since hte 6.1.3.x they limited it.
I always recommend having the DHCP server on a DHCP server not on the controller, not onthe switch not on the firewall... on a DHCP SERVER. Because they are resourses that the wireless controller could be using for something else....
I just recommend it having it if its for Guest users and they are not many...