ftp command in one line for wordpress -

i want place uploads folder wordpress on different server.

i read in wp-config.php had add:

define('uploads', 'folder move files'); 

and in order move files different server have place ftp argument instead of folder.

however keep getting 'unable create directory' error. tested ftptest.net see if ftp working , works correct.

this credentials enter:

host: <ip-adress> port: 21 username: user@domain.com password: <password> protocal: explicit ftp on tls 

i tried these 2 command same outcome of unable create directory:

define('uploads', 'ftp://user@domain.com:password@ip-adress:21'); define('uploads', 'ftp://user:password@ip-adress:21');