I can see the image on the notebook display normally until the login. Thereafter only having the monitor connected to the notebook via HDMI. After that the screen goes black. The problem seems to be related to Gnome as this happens with Gnome and Unity but not with KDE.
It happens even after removing the HDMI cable.
I changed some monitors settings and now I get the following message when I click Apply.
The message says:
GDBus.Errorrg.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SettingsDaemon was not provided by any .service files