I've figured out that I need to add the web addresses the server uses, like localhost:16001/admin console, to the list of trusted sites in Windows Explorer. So now I can get the Test and Start pages, and I can see the hosted files from a FM client running on the server, but cannot see them from any clients on our network. I suspect my Windows Server ignorance is the problem, so I'm still looking for helpful documentation.
Seems that port 5003 is somewhere locked in the network. FileMaker net goes over port 5003