If I use the file-upload in strapi.io, the filenames become a random name. Is there a way to preserve the original file name (eventually with random suffix) (e.g. for SEO)?
There is not at the moment without custom modification (extensions) to the upload plugin. The current system was put in place to ensure there was absolutely zero possibility of a file name conflict (Say two people upload a file called file01.img). A hash is created to make sure that one does not overwrite the other.