Serv-u FTP Server Open firewall cannot connect solution

Today friend asked a question, the firewall has set 21 port open, but the firewall opens, the FTP server is not connected. Using serv-u FTP Server software.

I remember having encountered the same problem before, and then checking the data, finally turned over to the solution and shared the solution as follows:

Set the allowed passive mode of the site that is already configured, and then the PASV port range setting in the Advanced options for Serv-u Server management: 2000-2010

In this way, in the firewall settings, then the 2000~2010 port open on it.

Allow this total of 11 ports in the firewall, as well as FTP 20 and 21 ports, 13 ports altogether, protocol select TCP.

and try again.