different server port

Possibly. In https://codex.www.ads-software.com/Editing_wp-config.php it mentions this:

define('FTP_HOST', 'ftp.example.org');

In THEORY you can add that line to your wp-config and define a port, but I don’t know if that would actually work.

define('FTP_HOST', 'ftp.example.org:22');

Maybe?

I will give it a try and let you know. thanks.

Okay I tried a number of combination’s. The other issue seems to be that I use sftp and it only allows ftp. the code you provided di allow me to change the port. so one step forward.

Add in define('FTP_SSL', true); maybe?

It seems that this enables ftps (ssl) but I am using sftp which I think is a different algorithm?

They are different, though sometimes SFTP ‘works’ with FTPS (SSL).

Can’t hurt to try ??