NPS error 18 after moving NPS server

Question

I have Always on VPN setup on a server and NPS on a domain controller. I was in the process of decommissioning my DC with NPS so I exported my NPS settings and imported them into the new DC. After doing that I restarted NPS then on my VPN server in RRAS I opened Properties and changed the RADIUS authentication server from the old DC to the new one. Problem is that when I did that I didn't realize there was a shared secret.
Now when people connect to the VPN I get error 18 in the event viewer on the new NPS server. I tried reverting back to the old NPS server, but I'm getting the same error.
If I don't have the shared secret for that RADIUS server what are my options? (I have the backup of both the NPS and RRAS config)

Answer 1

Okay, after changing the NPS and RRAS shared secret it's working again under the old NPS server. My only issue now is that when I try using a different NPS server I get an end user certificate error.

Answer 2

Hello there,

What is the exact certificate error you are getting ?

Please try these two things separately to see if the issue is gone:

1. Enable, or disable the "Message Authenticator" option in the settings of your defined radius client on your NPS Server, and try to see if the issue is resolved.
2. Add the PEAP authentication method, and try to see if the issue is resolved.

I hope this information helps. If you have any questions please let me know and I will be glad to help you out.

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