Please see this question for an explanation of my setup. https://www.experts-exchange.com/Networking/Q_21536734.html
I have resolved the networking issues by adding a switch. It connects the existing network to the cable modem, and should connect the new server to the cable modem, but doesn't appear to work. When I configure the server with the proper static IP/DNS/Gateway/SubNet information, I'm unable to see it from outside the network. In fact, if I leave DHCP enabled, it actually finds our DHCP server and obtains an IP. This means that the server is finding the VPN/router and the rest of the network, and using it. As far as I understand, this shouldn't happen.
Has anyone had a similar experience? I'm getting to the end of my neworking knowledge, and am running out of ideas.