Why do we get the error "425 Failed to establish connection" after logging into vsftpd server?

Issue

After logging into the vsftpd server, we get an error 425 Failed to establish connection when running ls or dir or put.

# ftp 192.168.0.1
Connected to 192.168.0.1.
220 (vsFTPd 2.0.1)
Name (192.168.0.1:(none)) dcc
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
200 PORT command successful. Consider using PASV.
425 Failed to establish connection.