Prova così:

codice:
'ftp' => [
    'driver' => 'ftp',
    'host' => 'ftp.server.com',
    'username' => 'USER',
    'password' => 'PASS',
    'root' => 'www.server.com',
    'passive' => false, 
    'ignorePassiveAddress' => true,
],