Hello Simon
Thanks for your answer.
Here is the output of the release command

Code:
cat /etc/*release
SUSE Linux Enterprise Server 12 (x86_64)
VERSION = 12
PATCHLEVEL = 3
# This file is deprecated and will be removed in a future service pack or release.
# Please check /etc/os-release for details about this release.
NAME="SLES"
VERSION="12-SP3"
VERSION_ID="12.3"
PRETTY_NAME="SUSE Linux Enterprise Server 12 SP3"
ID="sles"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:suse:sles:12:sp3"
The only configuration that I made was to change the vnc port.
I use "VNC Viewer" and "TightVNC Viewer" on Windows 10, and both of them visualize a black screen.
Regards
Marco