ftp bandwitch

My Proxmox is a part of VPN. Connection between 2 sites is 100Mb/s I want to upload my VM backups to external FTP server. I tried ftp, wput etc. For example this: wput $FILE ftp://$FTPUSER:$FTPPASS@$FTPHOST:/$FILENAME The problem is that the upload is always somehow limited to 20Mb/s. Does not...