Method 1: NAT Reflection¶. In order to access ports forwarded on the WAN interface from internal networks, NAT reflection must be enabled. In order to do this, navigate to System > Advanced, Firewall/NAT tab. On that page, select Pure NAT for NAT Reflection mode for port forwards, check Enable NAT Reflection for 1:1 NAT, and check Enable automatic outbound NAT for Reflection.
Openwrt Iptables