Hello,
Sorry for a long delay.
As I see now you’re using a domain name logopädie-sprachspatz.de and in Appearance > Menus you’ve written http://www.xn--logopdie-sprachspatz-fzb.de/ . So please change url to http://www.logopädie-sprachspatz.de/ in Appearance > Menus.
Thank you.
Regards,
Eva Kemp.