diff -up ./lib/ssl/sslsock.c.ssl2hello ./lib/ssl/sslsock.c
--- ./lib/ssl/sslsock.c.ssl2hello	2021-06-03 15:39:52.237945867 -0700
+++ ./lib/ssl/sslsock.c	2021-06-03 15:43:21.746203666 -0700
@@ -90,7 +90,7 @@ static sslOptions ssl_defaults = {
     .enableDtls13VersionCompat = PR_FALSE,
     .enableDtlsShortHeader = PR_FALSE,
     .enableHelloDowngradeCheck = PR_FALSE,
-    .enableV2CompatibleHello = PR_FALSE,
+    .enableV2CompatibleHello = PR_TRUE,
     .enablePostHandshakeAuth = PR_FALSE,
     .suppressEndOfEarlyData = PR_FALSE,
     .enableTls13GreaseEch = PR_FALSE,