Eddie's Blog: Configuring VCSA 6.5 Backup Lessons Learned
You are directly dumping the backup file to the FTP and not to any specific folder inside the ftp?
Is there any firewall in the FTPServer ? Can you try restarting ftpservice and also run the command curl -u <ftp user>:<password> -l <ftp server> from the above article to validate the same
Thanks,
MS