Comment 17 for bug 1281250


The problem is simple.
If you take a Wireshark trace you immediately see the issue.
You will have to filter on VNC.
The supported security type which is given for 14.04 is "type 18, TLS".
For 13.10 we see two types, "type 18, TLS" and "type 2, VNC".

The "type 2, VNC" is used by your VNC viewer.
So adding type 2 in the proposed supported security types will solve this bug.