Wireless instability observed on C9120AXE | 5520 WLC

[jktan-1110]

Hi Wireless Community, 

I am facing a weird wireless instability issue where endpoints will just random disconnects and I am getting no where to start the troubleshooting process. 

Current wireless network environment: 

AP Model: C9120AXE

AP Mode: Flexconnect

WLC Model / Version: 5520 / 8.10.190.0

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For the endpoint keep facing wireless disconnection issue: 

Endpoint Model: Dell Latitude 5430

Endpoint OS: Win 10 x64bit

Wireless NIC: Intel(R) Wi-Fi 6E AX211 160MHz

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Multiple endpoints is facing the issue, AP has been rebooted, configuration checked but nothing stood out. 

Can anyone enlighten me on how to begin the troubleshooting for the issue? 

Thanks much! 

Regards,

JK

[marce1000]

  - Have a checkup of the 5520 WLC controller's configuration using : 
          WirelessAnalyzer input (procedure) for AireOs controllers
    and feed the output from that into Wireless Config Analyzer

  -   Further engage in client debugging according to https://www.cisco.com/c/en/us/support/docs/wireless/wireless-lan-controller-software/213258-collect-debugs-from-wireless-lan-control.html
   Client debugs can be processed and analyzed with Wireless Debug Analyzer

   - Make sure wireless coverage is sufficient

  - Make sure the client's wireless drivers are up to date , 

 M.

[jktan-1110]

Hello Marce, 

Thank you for the tools and advice! 

For clarification on 2 points below: 

   - Make sure wireless coverage is sufficient - YES

  - Make sure the client's wirelessdrivers are up to date - CONFIRMED

I will share debug details after running through the tools mentioned. 

Best regards,

JK

[marce1000]

  - Ok , beside the client debugs also take care of the first item :
                - Have a checkup of the 5520 WLC controller's configuration using : 
          WirelessAnalyzer input (procedure) for AireOs controllers
    and feed the output from that into Wireless Config Analyzer

 M.

[jktan-1110]

Done that, as the issue is random and not easily re-produce, the client debugs only shows basic DHCP traffic without much details, as for the Config Analyzer nothing stands out too. 

[Leo Laohoo]

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@jktan-1110 wrote:
Wireless NIC: Intel(R) Wi-Fi 6E AX211 160MHz

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What firmware is the wireless NIC on? 

[jktan-1110]

I am requesting the WLAN report from client, it takes time to get it. 

[Rich R]

Don't know if you got that report yet but see this is where you should be looking for the latest driver:
https://www.intel.com/content/www/us/en/download/19351/intel-wireless-wi-fi-drivers-for-windows-10-and-windows-11.html

Other possible causes of issues:
- External interference or even something like Meraki containment feature which one of the neighbours might have turned on without understanding impact (illegal in most countries).
- Actual or false positive radar detection by APs on DFS channels.  What channel width are you using?  The wider the channel width the higher the risk of false positive radar detection.  9120 is supposed to be better at excluding those false positives but you might want to think about more sensible channel width like 20 or 40 Mhz if you've been trying to use 80 or 160 MHz.  Keep in mind that some types of motion sensors (lighting, doors, security) use radar which can cause this too.

[jktan-1110]

Thanks Rich!

As for your question on the channel-width, I can confirm it runs on 20Mhz. 

For the WIreless Driver, yes the endpoint is running on latest intel wifi driver.

But the issue still persisted in terms of wireless drop. 

I will follow this link: https://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/200480-Troubleshooting-Guide-for-Wireless-Clien.html

and provide the necessary output for further investigation.

This has been ongoing for quite a while and the issue is not easy to reproduce, multiple captures didn't clearly indicate the issue.

[Leo Laohoo]

Is 802.11ax enabled in the WLC?  

If it is, turn it off.

[MHM Cisco World]

Wireless NIC: Intel(R) Wi-Fi 6E AX211 160MHz <<- 
this NIC is use wifi 6E can I see WLAN config (share screenshoot)

MHM

[jktan-1110]

sorry which WLAN config are you referring to? On the endpoint?