For every project in our organization there is a SharePoint site. The default document library within that site contains all documents pertaining to a project. Some of the files are supposed to be visible only to users within the organization, some to external users that are given access to the SharePoint site.
This is supposed to be regulated through a yes/no column called External. External users are only supposed to see the items where the External column has a value of yes, none of the others.
Just moving the files to an additional document library on the site is not an option, as everything is supposed to be in one library.
I already tried out creating a web part showing the document library with a restricted view on another page with audience targeting only the security group containing the external users, but they can just change the view to any other.