FTP : connection failed to LIST, Failed to retrieve directory listing

The following error occured/hang trying to connect to FTP server:

Status:    Connected
Status:    Retrieving directory listing…
Command:    PWD
Response:    257 “/”
Command:    TYPE I
Response:    200 Switching to Binary mode.
Command:    PASV
Response:    227 Entering Passive Mode (xxx,xxx,xxx,xxx,xxx,xx)
Command:    LIST
Error:    Connection timed out
Error:    Failed to retrieve directory listing

This is probably because you are trying to connect to a “active” FTP server using “passive” mode.  Set your FTP client to active mode.