The Elektron RADIUS service implements the Remote Authentication Dial-In User Service. This is a common protocol used to provide centralized user authentication to a wide variety of network devices. As its name implies, RADIUS was initially designed to provide services for banks of dial-in modems, but it has expanded to include other devices such as Wi-Fi access points and VPN concentrators.
The RADIUS service implements basic RADIUS types, including PAP, CHAP, MS-CHAP, MS-CHAP-V2, EAP-MS-CHAP-V2, and EAP-MD5-Challenge. The higher level, Wi-Fi specific RADIUS protocols PEAP, EAP-TTLS, EAP-TLS, EAP-FAST, and LEAP are implemented in their own services.
You may choose which authentication types are enabled, but at least one type must be enabled in order for the RADIUS service to run.