chore: turned off ECN by default

config/config.go

@@ -482,6 +482,11 @@ func UnmarshalRawConfig(buf []byte) (*RawConfig, error) {
 				"www.msftconnecttest.com",
 			},
 		},
+		Experimental: Experimental{
+			// https://github.com/quic-go/quic-go/issues/4178
+			// Quic-go currently cannot automatically fall back on platforms that do not support ecn, so this feature is turned off by default.
+			QUICGoDisableECN: true,
+		},
 		Sniffer: RawSniffer{
 			Enable:          false,
 			Sniffing:        []string{},