-## Enable this option if you encounter any MTU problems
-## e.g. some websites work, others do not, submitting
-## forms causes problems, ...
-# option mtu_fix 1
+# We need to accept udp packets on port 68,
+# see https://dev.openwrt.org/ticket/4108
+config rule
+ option src wan
+ option proto udp
+ option dest_port 68
+ option target ACCEPT
+
+# include a file with users custom iptables rules
+config include
+ option path /etc/firewall.user