This is because the FTP-data port is blocked by a firewall.
1. Make sure that passive mode is enabled (vsftp enables it by default). Check the file /etc/vsftpd/vsftpd.conf, for the following lines
2. Also check whether the passive port range is open in the firewall. You can limit the port, for example 10000 to 11000, by adding the following lines in the file ‘/etc/vsftpd/vsftpd.conf’.
3. Restart vsftp service in server
4. Open the specified port range in the firewall (Iptables) too.