Add iptables rule to add miniupnd rules to forward chain.

Fixes #10043.

src/initscripts/init.d/firewall

@@ -252,6 +252,7 @@ case "$1" in
 	# upnp chain for our upnp daemon
 	/sbin/iptables -t nat -N UPNPFW
 	/sbin/iptables -t nat -A PREROUTING -j UPNPFW
+	/sbin/iptables -A FORWARD -m state --state NEW -j UPNPFW
 	# This chain only contains dummy rules.
 	/sbin/iptables -N UPNPFW