Wireless strengh drops

[trih]

I am new at troubleshoting on Cisco access points

I have 20 9120 APs, one of them is running as a controller.

Users experience wifi strengh dropping and being drop from a connected AP and graped by another AP. Some users don't have network connection others do.

Where should I start troubleshoting?

[patoberli]

This can be many reasons for this issue. First of all I'd try to reproduce it with a laptop with current wi-fi drivers. 

If you can reproduce it, check if you run a recent software release, I recommend either 17.3.5a or the latest 17.6.x release. 

If that doesn't help, create a radioactive trace of one of the clients (under Troubleshooting) and upload the file here: https://cway.cisco.com/wireless-debug-analyzer

[Leo Laohoo]

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@trih wrote:

Where should I start troubleshoting?

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1. What is exactly the problem?  (HINT:  Get the story straight.)
2. Someone must independently verify this behaviour with their own wireless client?
3. What radio is this happening on?
4. What firmware is the controller on?
5.  If the problematic wireless client is Windows-based, what is the complete output to the command "netsh wlan show drivers"?
6. Is this affecting one wireless client or multiple wireless clients? 

[trih]

The AP i am trying til troubleshot is in a classroom and all the students experience the issue.

The clients signal strenght, the teory is the claasroom AP goes unresponsive and clients at handed over to another AP.

When I try to run a Radioactive trace on the AP I get this error Not enough free memory to run this command, cancelling ...

[patoberli]

Which software release do you have in use?

The not enough free memory error doesn't sound nice at all and should be looked at in detail. 

[JPavonM]

Which is common between all students? Are they using the same device? I have troubleshooted similar behaviour with laptops using Mediatek MT792x chipset as they were seeing a signal drop when roaming. this was fixed with a driver update to latest version.

Are you using eWLC with Cisco APs? I've seen this "Not enough free memory to run this command" error in some releases so update them to latest TAC recommended 17.6.3.

SIDE NOTE: even if the devices are not managed, this doesn't mean they cannot be updated, so ask them to upgrade firmware (if tablets) or chipset drivers inside OS'es.