Needed in Chrome version >= 74 as Chrome dropped support for v1.0:
https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/discuss-webrtc/yr6gbAgWsKo/9X5vQb8kGAAJ

Using old v1.0 DTLS if 1.2 is not available or legacy DTLS
wanted explicitly. To request old DTLS set variable

	<action application="set" data="legacyDTLS=1"/>

Note: requires openssl 1.0.2 or later for DTLS v1.2 support