FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
While using RADIUS in addition to another auth server for authentication, FortiGate sometimes uses the wrong policy. The RADIUS server is not mentioned in the group but authentication still occurs through the RADIUS server.
See documentation for more information on RADIUS server authentication:
The Fortinet Security Fabric brings together the concepts of convergence and consolidation to provide comprehensive cybersecurity protection for all users, devices, and applications and across all network edges.