FTP / SFTP Troubleshooting
From XTENTO Support Wiki
If your server uses SELinux, you may be affected by this: http://www.linuxquestions.org/questions/red-hat-31/centos-5-3-php-ftp_connect-working-command-line-only-758922/
SFTP and PHP 7+ and Timeouts/failed connections
Possible error message: Detailed Error: This is not implemented
- Make sure you have the latest module version installed.
- Make sure you have libsodium installed.