diff --git a/openmptcprouter/files/etc/uci-defaults/2020-omr-vpn b/openmptcprouter/files/etc/uci-defaults/2020-omr-vpn
index ef15c5a1e..789e47d21 100755
--- a/openmptcprouter/files/etc/uci-defaults/2020-omr-vpn
+++ b/openmptcprouter/files/etc/uci-defaults/2020-omr-vpn
@@ -61,7 +61,12 @@ if [ -z "$(uci -q get openvpn.omr.ping_restart)" ]; then
 		set openvpn.omr.ping_restart=60
 		commit openvpn
 	EOF
-
+fi
+if [ -z "$(uci -q get openvpn.omr.tun_mtu)" ]; then
+	uci -q batch <<-EOF >/dev/null
+		set openvpn.omr.tun_mtu=1420
+		commit openvpn
+	EOF
 fi