Hi Adrian,
thanx a lot for your suggestions and sorry for the delay, I had to focus on other stuff recently.
I went through the posts and those that are included in them and basically tried to google all info about this issue.
Unfortunatelly I wasn't able to solve it. It's probably due to my insufficient knowledge of how nginx works.
But as I wrote, with another CMS (MODX), it works fine, all routes and subroutes are accessible.
One hint for those testing on Windows, localhost, I created a bat files to start/stop MySQL, nginx and PHP (sth. like start-server.bat and stop-server.bat) and they HAVE TO BE placed in the same dir as nginx.exe, as someone suggested somewhere, to avoid error messages and enable running nginx properly, just remember this.
If anyone bumped into the same problem, that subroutes are not accessible, and found a solution, a suggestion would be appreciated.
Thanx a lot again. Luke