AP backup tunnel not establishing

[Andre_Brits_Kan]

Hi Community

We have two C5210 Controllers configured in a High Availability cluster.
The solution is configured as a Primary/Backup solution, with all the AP's homing to the first controller as the primary and the secondary as the backup.

We have just over 600 AP's.

On the second controller we see the following error for random AP's.
 

The AP can reach both controller so this is not a routing error as refered to in the below post:
https://extremeportal.force.com/ExtrArticleDetail?an=000064655

Any ideas?

Regards

[Ronald_Dvorak]

Hi Andre,

just to make sure ... you are talking about Availability with Fast Failover enabled ?

[David_Choi]

Hi Andre,
Did you configure "Wireless Controller Search List" in all APs as below?

Above configuration would be recommended in HA environment. Please ensure that the IP address of primary controller should be located in upper side and bottom side for secondary controller.

And also please check followings:

If there is any blocking point for UDP port 13911 between APs and secondary controller. if Secure tunnel is enabled on thoes APs (please disable if it is not neccessary)

Can you also show us the screen of "AP availability" (Report > APs > AP Availability)?

[Nathiya_Munuswa]

Hi Andre,

What is the firmware version running on the controller?

Regards,
Nathiya M