Users experience intermittent WLAN drop happening on WLC9800L

[yum3372]

Hi guys,

We're using WLC9800L and AP91xx, AP37xx in our office. 

Some users experienced WiFi drop intermittently while using it. So I checked WLC logs with client MAC address.

And they all show the log messages as below.

2023/07/03 15:15:42.369312 {wncd_x_R0-0}{1}: [client-orch-sm] [20491]: (note): MAC: 50eb.7135.xxxx Client delete initiated. Reason: CO_CLIENT_DELETE_REASON_MN_DEL_CHANNEL_CHANGE, fsm-state transition 

2023/07/18 16:11:16.422930 {wncd_x_R0-0}{1}: [client-orch-sm] [20491]: (note): MAC: f47b.093b.xxxx Client delete initiated. Reason: CO_CLIENT_DELETE_REASON_MN_DEL_CHANNEL_CHANGE, fsm-state transition 

What does that mean 'Reason: CO_CLIENT_DELETE_REASON_MN_DEL_CHANNEL_CHANGE'?

And why does it happen?

Please somebody help me.

[Leo Laohoo]

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@yum3372 wrote:

2023/07/03 15:15:42.369312 {wncd_x_R0-0}{1}: [client-orch-sm] [20491]: (note): MAC: 50eb.7135.xxxx Client delete initiated. Reason: CO_CLIENT_DELETE_REASON_MN_DEL_CHANNEL_CHANGE, fsm-state transition 

2023/07/18 16:11:16.422930 {wncd_x_R0-0}{1}: [client-orch-sm] [20491]: (note): MAC: f47b.093b.xxxx Client delete initiated. Reason: CO_CLIENT_DELETE_REASON_MN_DEL_CHANNEL_CHANGE, fsm-state transition 

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15 days between the two log entries?  

What firmware is the controller on?

[yum3372]

firmware version is 17.3.6.

the symtom has been occuring intermittently. I caught those logs when the issue happened.

What does CHANNEL_CHANGE mean?

[Leo Laohoo · Accepted solution]

AP changed channel but the WiFi client did not follow. 

Upgrade the WLC to 17.9.3 and try again.

[yum3372]

I can't.. we have 37xx APs.. so the version 17.3.6 is the latest one that supports 37xx.

Why do APs change the channel?  Can I fix it?

[JPavonM]

Cisco has introduced support for AP3702 on 17.9.3 again.

Additionally, check if connectivity issues happen when devices roam from one AP model to another, as they are from difffernt standards it is likely that the device will drop current connection to re-negotiate it again.

There is another issue that impacts Windows devices while roaming which is that the OS turns from using OKC to SKC when it roams, so it get's disconnected. Cisco has released a fix in 17.9.3 (APSP1) that patch this Windows behaviour until Micrsoft fix it on its side.

[Leo Laohoo]

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@yum3372 wrote:
I can't.. we have 37xx APs.. so the version 17.3.6 is the latest one that supports 37xx.

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2700/3700 support has been extended starting from 17.9.3 and will continued up to 17.12.X.  

[marce1000]

  - Have a checkup review of your WLC9800L configuration with the CLI command show tech wireless ; feed the output into 
                                          https://cway.cisco.com/wireless-config-analyzer/

    For the troublesome clients , do client debugging according to : https://logadvisor.cisco.com/logadvisor/wireless/9800/9800ClientConnectivity , you can have client debugs analyzed with :
                                                     https://cway.cisco.com/tools/WirelessDebugAnalyzer/

 M.

[yum3372]

Hi all,

I just analyzed my WLC and it showed below errors.

what should I do to address them?

[marce1000]

                       - You should correct the two first errors 'as they are explained....'

 M.

[JPavonM]

I don't think fixing those errors solve your issues.

Try code upgrade to 17.9.3 as previously advised, and perform new checks.

Also look for potential DoS attacks from neighbour networks, specially if there are Merakis managed by adminstrators with lack of knowledge on wIPS features that are enabling it becuase they think that way they protect.

Check logs on the AP3702s to see for massive disconnection events going on at some time, for all users.