I had some Drupal installations which I merged into a multi-site installation.
When they were single installations, I created a files in the root directory and set the system permissions for the directory and its content to 755. When I ran the security review, I got no errors.
Now I set up them as multi-site; the files directory is still in the root folder, and inside there also the site1, site2, site3 directories used from the single sites. When I set the system permissions to 755 and run the security review, I get an error that about some files in my public files directory which are writeable by the server.
When I set the files folder in the root directory as well as site1, site2, site3 to 555, the security review didn't report anything, but I got an error message from the Drupal status report because the public file system is not writeable from the server.
Do I need to set up the public files directory for multi-sites differently?