RealVNC Server, Android Viewer – Server did not offer supported security type

I had a bit of trouble getting some Android VNC viewers to connect to a Real VNC server on windows 7 today. The most common error message proffered by the viewers while trying to connect was:

Server did not offer supported security type

It seems this may be caused by Real VNC using some non-standard VNC extensions…

Anyway I found that I could get rid of the error message and get the VNC connections to work correctly by changing the following Real VNC Settings (see screen-shot below):

(a) Change ‘Authentication’ to ‘VNC Password’ (and configure a password)
(b) Change ‘Encryption’ to ‘Prefer on’

Note that the second change probably results in the connection being unencrypted so be careful if you are using this on a public network!