I would like to configure 1:1 NAT for my ISP modem connected to my OpenWRT WAN interface.
The modem IP address is 10.70.70.1 and I want to map it on my OpenWRT LAN bridge (192.168.64.0/24) with IP address 192.168.64.171.
My DHCP range for the LAN interface is starting from 50 and maximum number of ip assignments is 50 devices. (192.168.64.50-192.168.64.100)
Since the modem will get a static uniques 1:1 ip address outside of the LAN DHCP range IP address I persume it will never make IP address conflict with other devices.
Having that said I followed the guide at https://openwrt.org/docs/guide-user/network/wan/multiple_public_ips and it seems it is not compatible with NFTABLES or fw4 implementation that comes with the latest OpenWRTs.
I would like to know what is the fw4 (NFTABLES) equivalent of the implementation of the guide link or how can I implement my desired configuration on the OpenWRT router?