Transport Layer Security (TLS) 1.0 and 1.1 are formally deprecated as of March 2021. For more information, see https://tools.ietf.org/html/rfc8996.
This RFC changes the requirement to reject TLS 1.0 and 1.1 from “SHOULD NOT” negotiate these versions to “MUST NOT” negotiate.
The RFC lists the reasons for the deprecation in the “1. Introduction” section. These protocol versions are vulnerable to attacks and no longer considered secure.
The devices that still use TLS 1.0 and 1.1 must be reconfigured to use a minimum of TLS 1.2 or later versions.