If your seeing traffic to your wan with a dest of some random number, its prob just noise.
I would suggest you use something like canyouseeme .org and test say port 80.. You should then see this traffic on your wan. diag packet capture will validate that.
As KOM points out use of VIP would be say if your ISP gave you multiple IPs to use. On the LAN there really would never be a reason to setup a VIP, especially in a different network this would amount to trying to run multiple layer 3 on the same layer 2 which is a Borked config.
If what your saying is that your isp gave you a rfc1918 address of say 192.168.1.100 and they forward all traffic to that public address to this IP. You just need to setup pfsense wan IP with that IP, and point to the gateway they gave you. Then forward whatever ports you want to the network your using behind pfsense on its lan, it could be a 10 network or a 172.16-31 network or even a different 192.168 network.
This really should work out of the box with very min config. Set your wan IP, set your lan IP and big bang zoom bobs your uncle.