FortiNAC Computer/Machine authentication

Are you trying to configure PEAP with computer authentication? If yes, FNAC need to be joined in the domain like shown here: Technical Tip: MSCHAPv2 authentication, join FortiNAC in domain and checks for the authentications to work. This guide Machine Authentication includes all necessary steps.

You need to check if the authentication succeeds first, than use a simple User/Host profile to match with the Network Access Policy. The RADIUS logs will give more information about the authentication results. The details that are shown in the mentioned article can be later leveraged in case you want to limit host access based on RADIUS attributes.

Are you using PEAP/MS-CHAPv2? You should not be using that in 2025. It uses broken encryption and should no longer be used. Credential guard will block this by default on modern versions of Windows.