Shared link doesn't survive an umount and remount of external storage

Some of our users have folders that point at external storage - in this specific case SFTP-mounted external storage
and can share links from this storage. However when that external storage is unmounted and then remounted
(same location, same path) the shared links no longer work. I’m guessing it’s because the underlying mount id
has changed - would that be the reason or is there more to it than that?