Thanks for the replies.
I was able to get some help on this from Support and finish the configuration.
To restate my problem, I wanted to pass my 5 Internet Route-able IP addresses to different servers inside my LAN.
x.x.x.341 --------> 192.168.12.25 (dns ns1)
x.x.x.342 --------> 192.168.12.26 (Mail, ns2)
x.x.x.343 --------> 192.168.12.27 (Security DVR)
x.x.x.344 --------> 192.168.12.28 (MX2)
x.x.x.345 --------> 192.168.12.29 (Web & LAMP)
It wasn't apparent to me how I should configure to support this. I knew I could NAT off of my single .341 WAN address, but I didn't know how to bind to the .342-.345 addresses.
This configuration is accomplished by using IP Aliasing and Firewall Rules.
Add an IP Alias for each additional IP similar to the following. Determine what mask is required for your range.
WAN x.x.x.342 255.255.255.248
Part 2 is create a Firewall Rule with a NAT mapping. Something similar to the following.
From Zone Insecure (WAN)
To Zone Secure (LAN)
Service <Select the appropriate service>
Action Always Allow
Source Hosts Any
Log <You decide>
Destination NAT Settings
Internal IP Address 192.168.12.25 <---- One of your internal addresses you want map to
Enable Port Forwarding Off
External IP Address WAN1 The drop down will display a list of available external WAN addresses that you added in the IP Aliasing. Once selected, it will just display WAN1
Repeat a rule for each service and external address.
Again, thanks for the initial replies. I simply got busy and didn't get to reply back right away.