diff --git a/openmptcprouter/files/etc/uci-defaults/1980-omr-firewall b/openmptcprouter/files/etc/uci-defaults/1980-omr-firewall
index 7696c150a..416122ec5 100755
--- a/openmptcprouter/files/etc/uci-defaults/1980-omr-firewall
+++ b/openmptcprouter/files/etc/uci-defaults/1980-omr-firewall
@@ -85,6 +85,11 @@ if [ "$(ubus call system board | jsonfilter -e '@.board_name')" = "bananapi,bpi-
 	EOF
 fi
 
+uci -q batch <<-EOF >/dev/null
+	set firewall.@zone[0].mtu_fix='1'
+	set firewall.zone_vpn.mtu_fix='1'
+EOF
+
 rm -f /tmp/luci-indexcache
 
 exit 0