Help: terminal devices under AP3600 are always disconnected randomly

[AndyFeng]

1. Equipment:
WLC: AIR-CT5508-K9 (Software Version: 8.5.151.0)
AP: AIR-CAP3602E-C-K9 (Boot Version: 12.4.23.0, IOS Version: 15.3(3)JF10$, Mini IOS Version: 8.0.115.0)
2. Fault phenomenon: When some terminal devices are connected to the AIR-CAP3602E-C-K9 model AP, the connection is always dropped randomly. There are also 2800, 3700, and 3800 series APs under the same WLC, and they basically do not have the above problems. When the terminal is disconnected, sometimes all other terminals under the same AIR-CAP3602E-C-K9 AP are disconnected, and sometimes only part of the connection is dropped. The same problem occurs in multiple areas, all of which are APs of the AIR-CAP3602E-C-K9 model.
3. Question: Are there compatibility issues between AIR-CT5508-K9 and AIR-CAP3602E-C-K9, such as hardware? system version?
4. Question: Does AIR-CAP3602E-C-K9 have similar bugs?
Looking forward to the issue being resolved, thanks!

[marce1000]

 - Have some client debugging for the involved terminal devices, which you can have  analyzed with : https://cway.cisco.com/tools/WirelessDebugAnalyzer/

 M.

[patoberli]

This might be some bug you are hitting. I recommend first to upgrade to the latest 8.5 release. Here the release notes:

https://www.cisco.com/c/en/us/support/wireless/5500-series-wireless-controllers/products-release-notes-list.html

[Rich R]

Remember the 3600 APs are already way past the end of software maintenance milestone and went end of support at the end of 2021:

https://www.cisco.com/c/en/us/products/collateral/wireless/aironet-3600-series/eos-eol-notice-c51-737511.html

nd of SW Maintenance Releases Date: HW*

The last date that Cisco Engineering may release any final software maintenance releases or bug fixes. After this date, Cisco Engineering will no longer develop, repair, maintain, or test the product software.

December 29, 2017

So although the latest 8.5 software still supports those APs Cisco haven't been testing them on new releases for the last 4+ years.  Upgrading might help or might not and TAC will not support them at all.

Back to technical stuff - like others have said you need to do some client debugs, check the WLC logs, see whether APs have crashed etc.  All the basic troubleshooting.

Regarding your questions 3600 and 3700 are fundamentally similar technology - they both run IOS so bugs are likely to affect both.  But 3600 is 802.11n and 3700 is 802.11ac so there could be differences in radio firmware.  The problem you're describing sounds more like an AP crashing occasionally to me.

[AndyFeng]

Thank you very much for your answer. In the near future, I will replace the AP3602 with the AP2802 for observation. In my impression, when there is a disconnection failure, what I see on the WLC is the prompt of the association failure. If I encounter it later, I will upload the relevant attached screenshots. I have another question, if I want to check the logs, should I check the logs on the WLC or the AP? I've tried looking at the relevant logs, but they're all very short-lived and don't have any useful information.

[AndyFeng]

Thank you very much for your answer. In the near future, I will replace the AP3602 with the AP2802 for observation. In my impression, when there is a disconnection failure, what I see on the WLC is the prompt of the association failure. If I encounter it later, I will upload the relevant attached screenshots. I have another question, if I want to check the logs, should I check the logs on the WLC or the AP? I've tried looking at the relevant logs, but they're all very short-lived and don't have any useful information.

[Rich R]

For AP crash info: https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-8/config-guide/b_cg88/debugging_on_cisco_access_points.html#ID1900

For logs: https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-8/config-guide/b_cg88/configuring_system_and_message_logging.html

And obviously connecting a console to an AP will ensure you capture everything from the AP that may not always reach the WLC.

[AndyFeng]

Hi

I recently made a new discovery, I found that a computer with an unstable network connection is not supported by Cisco CCX, while other computers on the same access point are supported by CCX. And I found that intel company has instructions about CCX, if the wireless network card driver version is too new, it will not be supported by CCX. I'm not sure if this has anything to do with the network drop issues I'm having.

[patoberli]

It should not. But because CCX is anyway not anymore supported by most
vendors and cards, you can try to disable Aironet IE under the Advanced SSID
settings, if not already disabled.

[Rich R]

It's generally best to make sure you have the latest Intel driver installed.

What model of Intel adapter is it and what is the driver version? 

There were some problems with some Intel adapters recently which are only fixed in the latest release of the drivers - plenty of discussion about that elsewhere on these forums.

Regardless of any of that you should consider updating the WLC as per https://www.cisco.com/c/en/us/support/docs/wireless/wireless-lan-controller-software/200046-tac-recommended-aireos.html