|I would suggest you review your understanding of what routing and nonrouting is about. It would explain "I am unable to currently have both WAN and LAN IPs functioning on my network "|
Normally it is not advisable to put a server as a host directly on the internet.
Normally you only use one wan ip on the wan interface of your router and do nat to your lan. If you have a web or mail server you would forward ports via your router to those ip addresses. This is where doing ip reservations in the router pay off. Its a way of doing static ip assignments but using the lan ip not a wan ip.
You would get your isp to put in a mx record into dns for the mail and an A record for the web server.
You can't use 4 network ports in the server with your equipment.
"How do I setup a network to have WAN IPs go to some servers and have the desktops only use NAT?"
You would configure as this:
internet<>switch with static wan ip servers
internet<>switch<>router<>pcs with lan ip.
This puts the static wan ip servers as hosts on the internet. Better keep them patched, secured and software firewalled!
You may need to add route tables to the router for the pcs to communicate with the servers.
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