Unfortunately, the sound is not there. So I think you misinterpreted a few things.
I played with your website, and I don’t see “city” in the drop down menu (see attach.)
It is gone because I changed the css for that class to collapse and a margin of -20px. However, it should do this by itself, if this is the only category that one can choose.
The most important thing is: Only one city is being shown! All the other 10 cities are not showing here. But this is major.
and if I type “auto” and autocomplete with “Autoaufbereitung” as you did in your screencast, I can see three listings (see attach.).
The problem with this is that it shows a search result and not the category “Autoaufbereitung”. Thus, it creates duplicate content as we cannot use a rel=canonical nor can we use noindex for these search results as they do not appear in Yoast SEO plugin.
About the 404 error, it’s a permalinks error, it should be /standort/germany/nordrhein-westfalen/hattingen rather than /standortgermany/nordrhein-westfalen/hattingen , please check your permalinks settings in WordPress ( /wp-admin/options-permalink.php) and add a / at the end of the url (after %postname%), I believe this is the issue in your case 🙂
Yes, thats solved now