Hi,
what end device, android? Maybe easier. You use the internal AAA server?
For group, session time: Session Time in Minutes. client gets access for this amount of time on successful authentication, then the session will be removed
access-duration you can configure for user.
You need to check the use of this value. Is it a time to configure from first login to quit. Or is it a time during that the user is valid.
If you configure a user valid for 1 hour and he login after 50 minutes, the session is alive over this one hour maybe.
If you use session time, the value is valid after each authentication. If the client don't support fast roaming, session time maybe start after each roam.