VNC via VPN-connection does not work

```
What steps will reproduce the problem?
1. Establish VPN-connection (acitvate PPTP-encryption)
2. Connect to running TightVNC-Server
3.

What is the expected output? What do you see instead?
Very seldomly, a connection can be established (which is very unstable),
but most of the time it says "Establishing Handshake" forever

What version of the product are you using? On what operating system?
Latest version of android-vnc-viewer, Android 2.1

Please provide any additional information below.
Android-vnc-viewer works fine when I connect whithout VPN (at home). I
tried connection via VPN only in the office, where we have dual screen
displays. Changing the resolution did not help, so that I think, the
problem seems to be with the VPN-connection in combination with VNC. The
tunnel works... Thanks for you help, I really need to get this working.

```

Original issue reported on code.google.com by `jk.josef...@gmail.com` on 1 May 2010 at 8:15

Start by reproducing the reported sequence on Android 2.1: activate the PPTP VPN, connect to the running TightVNC server, and compare it with a connection without VPN. Investigate the handshake behavior and verify that the VNC connection becomes stable over the VPN; the issue mentions no files or tests to begin with.

Escrito por el modelo de indexación a partir del texto del issue.