Ensure that the credentials you have been provided with are accurate before proceeding to validate the backups. If your cPanel server is equipped with a firewall, ensure that it is not obstructing outgoing connections to the OVH server. Adjust the firewall rules accordingly or consider temporarily disabling it before attempting the process again.
Make certain that your FTP server supports the MLSD (Machine List Directory) or LIST commands. If the FTP server does not support these commands, the backup system cannot use the FTP server as a remote FTP server.
Unix-supported FTP servers, such as ProFTP and Pure-FTPd, support these commands.