Código PHP:
$connection = ftp_connect($server);
$login = ftp_login($connection, $ftp_user_name, $ftp_user_pass);
if (!$connection || !$login) { die('Connection attempt failed!'); }
$upload = ftp_put($connection, $dest, $source, $mode);
if (!$upload) { echo 'FTP upload failed!'; }
ftp_close($connection);
Con ftp_put sí que me funciona, ni copy ni move_uploaded_file.