iptables -I FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
iptables -I FORWARD -i br1 -o br0 -m state --state NEW -j DROP
iptables -I FORWARD -i br1 -d 'nvram get lan_ipaddr'/'nvram get lan_netmask' -m state --state NEW -j DROP
iptables -I INPUT -i br1 -m state --state NEW -j DROP
iptables -I INPUT -i br1 -p udp --dport 67 -j ACCEPT
iptables -I INPUT -i br1 -p udp --dport 53 -j ACCEPT
iptables -I INPUT -i br1 -p tcp --dport 53 -j ACCEPT
iptables -t nat -I POSTROUTING -o 'get_wanface' -j SNAT --to 'nvram get wan_ipaddr'
Adicione isto ao seu firewall e execute este comando e salve.