On the core's orbiter, click on the "Advanced" button (I think I've got that right, the one with all the reset buttons at the bottom) and find "Network Settings" (again, I think I've got this right). If you're in the right place, you should see two buttons saying something along the lines of "Use Static" and "Use DHCP". Try clicking on the DHCP one, and see if that gives you any joy.