[solved] VNC over OpenVPN didnt work - MTU problem

[Chaka]

Hello guys,

little note for others, because it took me some time to narrow down the problem.
I couldn't get a stable connection to an UltraVNC Server via OpenVPN tunnel. Means, the viewer did connect but I didn't see the remote screen. Mostly the viewer showed some color fullscreen, sometimes blue, sometimes red or grey. I think the color correlates with the choosen format and encoding within vncviewer settings. Maybe 10 seconds later the connection is lost, reconnection fails or I see the colored screen for a long time. Curious I could move the mouse at the remote machine (I sat next to it) but didn't see something in the viewer.

However it turns out to be an mtu problem through the vpn tunnel. At both ends the mtu differed because of a hybrid access network at one end and a simple Digital subscriber line at the other end. So I did set a lower fixed mtu within OpenVPN-config to fix that problem, e.g. mtu-tun 1300. Btw mssfix did not solve the problem.