Adding APs with software 17.6.4.56 to 9800 running 17.3.5.43

[DavidHutton0858]

Hi,

We have recently received two 9120 APs with software 17.6.4.56.  Our controller is running 17.3.5.43 and the APs don't seem to associate with the controller to downgrade the software.  Is this a know issue?

[Scott Fella]

Let me ask a question. Do you have any other ap's joined to the controller?  If not, then there can be an issue with how you setup you controller.  You can search the forum for other post regarding 9120's not joining a controller.  When you post questions like this, it is best to provide more information.  An output from the ap console while booting up the ap, will show you what is happening and why the ap isn't joining the controller.  Running a debug on the controller can also help to see if the ap is actually trying to join.

C9120AXI-E not joining C9800-40 - Cisco Community

[Scott Fella]

Here is a guide to help you start the initial troubleshooting.

Troubleshoot Catalyst 9800 AP Join or Disconnection Issues Flow - Cisco

[DavidHutton0858]

Hi Scott, We are were just adding 2 APs to an existing site.  It looks like we are being affected by the issue in the field notice below and a software upgrade is required.  The two new APs were manufactured in September and according to the below we need to upgrade to 17.3.6 to support the APs.  Thanks for the input

https://www.cisco.com/c/en/us/support/docs/field-notices/724/fn72424.html

[Scott Fella]

Just make sure you look at the compatibility matrix to make sure all your existing access points are supported on the image you plan to use.  The field notice you have is what many others have hit themselves.

Cisco Wireless Solutions Software Compatibility Matrix - Cisco

[Leo Laohoo]

Look at the back of the AP and determine the date of manufacture.  If the AP was manufactured after September 2022, the AP will not join the controller due to FN-72424.  The WLC will need to be upgraded to 17.3.6 or 17.6.4 or 17.9.2.

[Rich R]

Just be aware that there is a serious regression bug in 17.3.6 - see the links in my signature below.  You need to install the APSP with the fix for that after you install 17.3.6.  Always check the TAC recommended code - also link below.