SMC Networks SMC2804WBR V.2 - Manual (Page 73)

Advanced Setup
71
DMZ (Demilitarized Zone)
If you have a client PC that cannot run an Internet application
properly from behind the firewall, then you can open the client
up to unrestricted two-way Internet access. Enter the IP address
of a DMZ host to this screen. Adding a client to the DMZ may
expose your local network to a variety of security risks, so only
use this option as a last resort.