@KSVSachsen,
I suggest you downgrade to version 16.16.6, version 17.10.1 has been removed from the list of stable versions. This version was showing several bugs, mainly in performance.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
Please, if this post was useful, leave your kudos and mark it as solved.