Welcome SILadmin. As you stated that your server needs an internal IP, if it is directly connected to your router you can manually assign one from the DHCP scope that is on your router. This will enable your internal networked computers access with fewer routing statements on your router. It is not necessary to connect it directly to the SMC. Alternately, you can "turn off DNS and DHCP in the server," and directly connect both the router and server to the SMC and utilize DNS & DHCP from the SMC. Please let us know if you need further assistance with the configuration of the Comcast SMC Gateway.