Hello münsterorganist,
I have no experience with Dante myself, so I can't really help with that, I'm afraid, but there's absolutely no difference between Hauptwerk v5/v6 and v7 with regard to audio drivers/ASIO, or platform requirements/components [except that v7 is linked to a later version of the iLok libraries, which might possibly themselves be linked to newer versions of the Windows libraries, but I very much doubt that's relevant].
My only suggestions would be:
- Make sure that all available Windows updates are installed.
- Try (re-)installing the latest version of iLok License Manager ( https://ilok.com/ ).
- Try (re-)installing the latest version of your Dante driver/software.
- Reboot.