We have WISM controller running version 4.2.130. We are attempting to use an SSID with either A or G radio. This is not working for A radio but works for G. Looking at debug, i see that there is no dhcp info on the failed A radio connection. The client gets limited connectivity messege with that 169.x.x.x address indicating no dhcp. Once doing more testing, I figured that A radio works with WPA2 with TKIP. It does not work with WPA2 with AES. Is there a known issue or bug with AES, 802.11a, and DHCP?
Please create two seperate test WLANs lets says SSIDs test1 and test2 pointing to the same interface; the interface can either be an existing one or a new one with the WiSM performing DHCP. Configure Test1 to use only 802.11g in the radio policy and Test2 with only 802.11a. Set both WLANs to use L2 security WPA2-AES and nothing else.
Once you have done this let me know the results and I can help further.
From your initial post I am slightly confused as if you are using the same WLAN with both radios enabled pointing to only one interface, then DHCP should not be a problem for only one of the two radios as they have no part in this process. What is providing DHCP for your clients, server or WLC? Are you using only a single WLAN? What AP's are you connecting to?
Secondly the client will make the decision which encryption to use depending on the highest level available on the WLAN that it is capable of supporting, were you using the same client on both a/g connections?