Xibo Linux Ubuntu autostart

Hi,
I have a problem.
I want to run Xibo on a MiniPC Stick. On this stick runs the operating system Linux Ubuntu. I chose Xibo as the startup preference. The stick should also run via WLan.

So far so good. Everything works in principle. However, there is only a black screen when I run the stick via wifi, via LAN everything works so far. Why is that?