|The simple/smart method would be to buy a SOHO router and put it between the modem and the server. In fact, I would do so and also have it do DHCP for your network as well.|
This would have the added benefit of reducing the load on the server and free it up for more important things.
Do you have a second DC configured for redundancy in case something fails on the primary one?
At the risk of sounding rude, I'm going to comment on your lack of capitalization when you type. It looks very unprofessional and well, it makes you look barely literate. If you work in IT proper grammar, spelling and punctuation should be an important part of anything you write. Whether it's a procedure guide, technical document, or a question on a forum like this.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.