Radius Connection Issue

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Radius Connection Issue



We've been running on Radius wifi through an NPS for a while without issue, last Thursday the NPS server was rebooted and since then we've been unable to connect via Radius


All of the necessary certificates are still in place, shared secrets are the same and have been re-confirmed, and testing the radius connection from the SSID on meraki fails for all 3 AP's.


The NPS server pings from all AP's on the meraki dashboard, the server itself looks fine and there have been no changes to it apart from the reboot. We have tried subsequent reboots but no change.


There are no logs whatsoever on the NPS to show any connection attempts being made since the reboot, which sounds like the connection attempts are not reaching the server at all as it should be logging both failed and successful connections.


Has anyone seen this before?



4 Replies 4
Kind of a big deal
Kind of a big deal

Not seen this before. But I would start the following way:

  • Capture the RADIUS-traffic on the port to the NPS. There you see if the traffic reaches the NPS and if the server answers.
  • If there is only the RADIUS ACCESS-REQUEST and no ACCESS-CHALLENGE coming back, then the NPS refuses to talk to the AP.
  • If there is an ACCESS-CHAlLENGE coming back, look into the *next* ACCESS-REQUEST. The reason could be quite clear in the packet if the client refuses to talk to the NPS.
  • If the NPS directly  returns an ACCESS-REJECT, then it is matching a policy that denies access.

Thanks Karstenl


The capture shows one original "Access-Request" plus 2 more "Duplicate Request" entries no doubt due to it re-trying the connection, but there's no follow up Access-Challenge.


Thanks, I'll see if I can find out why it's not talking to the AP's

Kind of a big deal
Kind of a big deal

The #1 most common cause of this is the certificate has expired on the NPS server.

Kind of a big deal
Kind of a big deal

Windows update installed any updates at the same time it rebooted?

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