2013 – ‘Open with explorer’ via http makes Explorer crash

We currently have the effect that when clicking Open with explorer in a document library we can’t add / edit / change items. The folder opens but as soon as we try to add something the explorer.exe freezes. Same goes for mapping a library to a drive letter.

By default we access our intranet via http. About a year ago we added the option to access it via https.
And when accessing our Intranet via https everything works fine.

Anyone else has this feature/bug? Is there a way to fix it (a patch that might have been responsible)?

We use SharePoint 2013 on Windows Server 2012 R2. Client OS is Windows 10.