Hi Wilm,
Yes, this message seems to occur sometimes for new installations.
-Port 8100 need to be port forward.
-Wait 24h for the server to register.
-If still a problem I would recommend to do a clean installation. Start the installation program and select Remove. Go to C:\ProgramData\Moonware\Netcam Studio\Server and delete the content. If you have recordings in the Library you can keep that and add them later to to the Library again. You can also keep the file Lic.dat. Go to C:\Program Files\Netcam Studio - 64-bit and delete its content.
-Install NCS again with version 1.6.2 from Netcam Studio 1.6.2
-Henrik