You can direct inbound traffic by port in the firewall (at least that's what I've seen in Cisco and SonicWall) for servers inside the FW.

Was the original device in the CW database? If so, did you try deleting the original device from the database and rediscovering the new one?

If the router's interface is touching the ISP's public network, you're going to need one of their public IP's.Why won't the ISP let you buy more? Have you checked with other ISP's?Do all of your servers require external/public access to provide the ...