Cisco 9800 iPhone devices clients stuck in IP learn with 5 band

[Mohamed_Ibrahim]

Hi all,

We are experiencing a strange problem with our WLC 9800 running version 17.9.5. All iPhone devices can't obtain an IP address and get stuck on IP learn mode with the 5 GHz band. If we disable the 5 GHz band, the devices work fine with the 2.4 GHz band. This issue is only affecting iPhone users; and other devices are working without any problems. Please note that we use an external DHCP on our Cisco core switch.

Can anyone explain this behavior and identify the root cause?

[marce1000]

    - Have a checkup of the 9800 WLC configuration with the CLI command show tech wireless and feed the output to : Wireless Config Analyzer

   You can test an Iphone connection attempt to a specific  AP with  ; by using  this command first on the AP:
                          show  ap client-trace events mac aa:bb:cc:01:02:03 (the latter mac address must of course be changed to the iphone's mac address  ). Then during the connecting process (and later) follow up on the outputs shown or check the logs on the AP

   - Further engage in full client debugging according to https://logadvisor.cisco.com/logadvisor/wireless/9800/9800ClientConnectivity , these debugs can be analyzed with Wireless Debug Analyzer

  - Outputs from the commands mentioned in https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/217738-monitor-catalyst-9800-kpis-key-performa.html#anc5 can also be useful

  M.

[Leo Laohoo]

See if this is CSCvx47799 or CSCwa93009.