FreeRADIUS RADIUS crypto-agility was first mandated as future work by RFC 6421. The outcome of that work was the publication of RADIUS over TLS (RFC 6614) and RADIUS over DTLS (RFC 7360) as experimental documents. Those transport protocols have been in wide-spread use for many years in a wide range of networks. They have proven their utility as replacements for the previous UDP (RFC 2865) and TCP (RFC 6613) transports. With that knowledge, the continued use of insecure transports for RADIUS has serious and negative implications for privacy and security. This document formally deprecates the use of the User Datagram Protocol (UDP) and of the Transport Congestion Protocol (TCP) as transport protocols for RADIUS. These transports are permitted inside of secure networks, but their use even in that environment is strongly discouraged. For all other environments, the use of secure transports such as IPsec or TLS is mandated.