diff -up nss/lib/ssl/sslsock.c.ssl2hello nss/lib/ssl/sslsock.c
--- nss/lib/ssl/sslsock.c.ssl2hello	2020-07-22 17:54:31.498366114 +0200
+++ nss/lib/ssl/sslsock.c	2020-07-22 17:55:46.019824069 +0200
@@ -89,7 +89,7 @@ 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
 };