Best way to run a local Windows 2016 server and a remote NC installation in parallel?

Some of our employees use NextCloud. Now all colleagues want to enjoy the benefits of NC.
The problem: We cannot completely do without our local Windows server due to some proprietary industry solutions that have to be connected to a local path and generate a relatively large load.
At the moment we are unsure which option is best for our case:

  • local Windows server, shares must remain available locally
  • NC environment in the data center (incl. backup)
  • relatively slow Internet connection (theoretically 16MBbit/s, practically 1/3 of that)
  • 1.5 TB of existing data on the local server
  • Data growth (approx. 2-3 GB / week, e.g. images from employees in the field)
  • Each employee should load their documentation directly into the NC and edit documents if necessary (Collabora); devices: Win desktop, Win notebook, MacOS, Android, iOS
  • A new folder for a specific user group every 2-3 days
  • Use of files, calendar, tasks, Collabora

We have found the following variants:

(Variant 1) WinServer local + with NC client (own user)

  • so far NC-Client crashes every 1-2 days and has to be restarted
  • keeping a copy of all files on all clients is not possible due to the amount of data (virtual folder problem with Macs)
  • unsolved for us: keep more complex authorizations synchronized

(Variant 2) Integration of directories via WebDav/network drive

  • relatively slow

Does anyone have experience with this?