Hi Ahmed,
I have the same issue as well. Wireless clients sporadically lose their IPv6 RA information and no IPv6 RA can be seen on the clients wireless interface anymore. We are running WLC 5508 with 8.3.143 and are using Cisco 2602 and 1262 access points.
I have opened a case with TAC yesterday and we are investigating this now. Have you opened a case as well? We could exchange case numbers with private messages so Cisco can use this information in order to get more resources for debugging.
The issue is also reported here:
https://supportforums.cisco.com/t5/ipv6-integration-and-transition/ipv6-issue-on-wlan-with-wlc2504/td-p/2972551/highlight/false
CSCvh53814 is another issue with IPv6 RA but does not apply to our environment.
BR
Michael
