I would start with looking at the router logs by using
Like any cisco, if logging is enabled, you should see at least some
%DOT11 messages like
To enable logging with a 10kB buffer (default is 4096bytes):
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#logging buffered 10000
If nothing obvious appears from the logs, you could try to activate some debugs on the router:
router#debug dot11 ?
Content-Engine cisco content engine service module
Dot11Radio IEEE 802.11 WLAN
Service-Engine cisco application engine service module
aaa Authentication, Authorization, and Accounting
arp-cache ARP Cache
events IEEE 802.11 events
forwarding 802.11 AP forwarding
mgmt 802.11 Management
network-map Network Map
packets IEEE 802.11 packets
syslog Turn Off Dot11 syslog msgs
virtual-interface 802.11 virtual interface
That should help to troubleshoot the issue.
Be sure also to disable
logging console as logging on the serial console generates a cpu interrupt for any character (hence a high cpu usage), and prefer
terminal monitor if you're debugging from a vty (telnet/ssh).
A syslog server would be quite useful also. It will store all the logs from the router, and they can then be processed (script of some kind, your eyes...) on the server.
Hostname or A.B.C.D IP address of the logging host
router(config)#logging <ip of syslog server>