Thank you for your post.
I would first try opening all ports on the server. Try launching Admin Console again. If this fails, then change your firewall settings (if they exist) to allow all incoming connections and try again. If this fails, then make sure the admin_console_webstart.jnlp file is set to launch with /System/Library/CoreServices/Java Web Start.
Please let everyone know if this issue was resolved and what was the cause.