Topology：
(https://i.postimg.cc/HkG9pFmT/t0.jpg)
It sounds the "Outbound NAT" did not convert the LAN subnet(100.98.48.0/24) to its WAN interface address(192.168.103.2).
(https://i.postimg.cc/Z5xBjL82/t1.jpg)
I'm at host 100.98.48.63, trying to ping 192.168.103.1. At the same time capturing these ICMP packets in OPNsense, by using pftop -f 'net 100.98.48.0/24 and proto icmp'(see the snapshot below), I can see the outbound ICMP packets, all from 100.98.48.63 to 192.168.103.1 instead of my expectation to be converted to interface address(192.168.103.2).
(https://i.postimg.cc/rwkF0J8d/t2.jpg)
There are no any firewall Rule on LAN port inbound direction
(https://i.postimg.cc/63gNjC26/t3.jpg)
My next step is to going to change the NAT Address: interface address to WAN address, but I think both of them have the same IP address 192.168.103.2. Any ideas are very appreciated !!
(https://i.postimg.cc/d0p49n5F/t4.jpg)