I have the same problem.
Using putty from outside, I can get into the console logging on as root, and into a lynx-version of the server-manager, logging on as admin.
But a web-connection to server-manager ? No dice.
It worked just fine in 5.5 and 5.6
Through VPN it should be possible, but my results so far are nil, except for the W2K-box I worked from. That had to be reinstalled since it lost its network setup, and nothing could persuade it to rejoin the domain.