besux

Thanks a lot. The guide helped me a lot. I recommend everyone give it a read.

My solution in the end was simply put this:

1. Add a new user with password to Unraid. (Users - > Add User. Remember the credtials.)
2. On the Windows PC go to "Windows Credentials Manager" and make sure, that you have the login credentials of that user stored for the login to your Unraid-server.
 
As long as the settings of the shares you want to see and edit on your Windows-PC are set to "public", it seems to do the trick.

I'm still a bit baffled as to why this didn't just work with the original user. But okay.