How to get the vKVM console @Hetzner to work? It ain’t much of a surprise that it doesn’t work out of the box, because the advertised link directs you to a Java applet. That only displayed the header for me, on Linux and Windows 10. But fret not: there is a solution.
Fortunately, when vKVM is running, you can access it via SSH on Port 47772 with the given password. VNC should be listening on Port 47774, but it’s stunnled, so you can’t access it directly. QEMU-VNC is actually listening on Port 5901/tcp, so you have to tunnel you way in.
# ssh -L 5901:<remote_ip>:5901 -l root <remote_ip>
That should forward remote 5901/tcp to something you can access. Now run:
# vncviewer 127.0.0.1::5901
And no, the double colon is no typo! Now go, fix your problems and have fun!