Network Policy Service handles radius request and is used for controlling policy based access rules for network. This service exists only on Windows Server (2008-2019) operating system and does not require separate license.

NPS can log succesfull and failed authentication requests to Event Logs, Custom Views → Server Roles → Network Policy and Access Services

1. Check that loggin is enabled, open Network Policy Server, right click NPS (local) → Properties → there is two selection boxes to log successfull and failed request
2. If loggin still does not work, from elevated commandline run

auditpol /set /subcategory:"Network Policy Server" /success:enable /failure:enable