Hello,

we are using x2go server and clients both on Ubuntu 16.04. After configuring new clients on small single board boxes like a ZODAC Zbox or a Raspberry Pi 3 we observe severe screen redrawing problems an a very poor performance in video transfer. E.G. shifting a Thunderbird-window over a Firefox-window the latter remains scrambled with rests of Thunderbird.
We didn't run into that problem in our former installation based on Ubuntu 12.04. After searching for solutions in the compression method and the CPU-performance of the clients I occasionally found out that the problem disappears after connecting the client's monitor via VGA instead of a HDMI connection. The problem even disappears when a HDI/VGA-Adapter is used and the signal is fed to the monitor via an VGA-input. This was tested with different monitors. In our former clients we only used VGA connected monitors and so we could not see the problems.
The optical quality of a HDMI connected Monitor is notably better than that of VGA connected one, furthermore the VGA connection seems to become obsolete, so we would like to stay with HDMI.
What can be the reason and is there a way change the HDMI-output in to a suitable configuration?

Best regards
Reinhold