It all depends on your authentication model for your network. Is that server running any sort of Active Directory authentication services? If so you will need the DNS to automatically update from whatever DHCP is setting things. In that case it is FAR easier to let the Windows Server take on that role.
Just set the router with a static assignment for 1 IP, to the MAC address of the servers NIC, then limit the DHCP scope to that one IP.
Next on your server, set the DHCP scope to your entire subnet excluding the IP of the server itself, and the IP of the router.
FWIW, nice setup by the way. That Asus router is a nice one!