Where is archive.realvnc.com?

RealVNC strongly recommends customers use the most recent versions of VNC Server and VNC Viewer, available from the RealVNC download site

If you have a license for VNC Enterprise Edition or VNC Personal Edition version 4.6 or earlier, or need to download documentation, please contact our Support team. 

To better serve the open source community, VNC Open version 4.1.3 has been moved to GitHub at the links below:
VNC Open 4.1.3 Windows source

VNC Open 4.1.3 UNIX source

VNC Open 4.1.3 Java source