When called-station ID configured users are not able to connect on 2.4GHZ
Clients connecting to 2.4GHZ unable to connect to the radius authentication
Check if called-station-ID configured in the remote access policy in the radius server
Users are unable to connect to the dot1x SSID on 2.4GHZ
In the same time when users are connecting to 5GHZ it is working fine.
Check and see if Called-station-ID is configured in the remote access policy in the radius server configuration. If yes then make the below changes.
Generally the called-station-ID should be the BSSID of the AP. It should be the both BSSID (2.4GHZ AND 5GHZ) of the AP configured in the remote access policy server, otherwise if the request comes from the configured BSSID in the called-station-ID only will pass the authentication and others will fail.
Check the event viewer to understand the reason for the failure if it is unknown called station ID then check the below.
Here is the configuration in the Radius server.
Here is the process to add another BSSID in the network policy server.
Go to internal authentication service in radius server and click on patten matching syntax and chose match any one of the enclosed character
Then it should look like the below in the radius server remote access policy
After checking and making the above changes should fix the problem.