Are you talking about page jumps? Like did you setup a page jump and then add it to the menu?
https://en.support.wordpress.com/splitting-content/page-jumps/
No. here is the website in discussion.
http://ertumop.de/
the problem is with the “produkte” button in the menu. it is linked back to the homepage but for some reasons it dosen’t work
It looks like you added the link as just “#m1” when the link you wanted was “http://ertumop.de/#m1”
As such, whenever you are on a different page and click the link, it takes you to “http://ertumop.de/current-page/#m1”, which isn’t a real page for any page except the homepage.
Just go to the menu and add the link for produkte as “http://ertumop.de/#m1” instead of what you currently have, “#m1”