Before integrating the NPS plugin for VIP, make sure that after configuring NPS with a third-party application first-factor authentication works correctly. If there are issues with first-factor authentication when using NPS, contact Microsoft support.
The NPS plugin supports only the RADIUS PAP protocol. When using a client, ensure that the communication between the client and the NPS server occurs over RADIUS using PAP.
After the above two checks:.
Cert Location Check: The VIP certificate (downloaded in PEM format from VIP Manager) should be placed in the same location where the NPS plugin will be installed. For example, C:\Program Files\Symantec\NPS\certs.
“Run as Administrator” Check: Confirm that the NPS plugin installer setup.exe is run as an Administrator.
RRAS check: Ensure RRAS (Routing and Remote Access is not running on the same Windows system where NPS is installed.