NAS542 Help is Empty

Titule Posts: 2  Freshman Member
edited April 2019 in Personal Cloud Storage
On the NAS542-Desktop, there is a Help-Application ("Hilfe", it's the German UI).
Clicking it opens a new browser-tab (URL: http://zyxelnas/r51163,/desktop,/Help/wwhelp/wwhimpl/js/html/wwhelp.htm#context=Help&topic=Desktop) which is totally empty (besides a window-split from top to button on the left side).
Tried it on firefox and edge.

Looks like a configuration problem, how can I solve it?