When entering passive mode, there are some common errors seen. Most commonly, a failure to connect to the server results in a timeout with a log similar to this:
Status: Resolving address of $ftp-host
Status: Connecting to $ip-address:21...
Status: Connection established, waiting for welcome message...
Status: Initializing TLS...
Status: Verifying certificate...
Status: TLS connection established.
Status: Logged in
Status: Retrieving directory listing...
Response: 257 "/" is your current location
Command: TYPE I
Response: 200 TYPE is now 8-bit binary
Response: 227 Entering Passive Mode ($ip-address)
Error: Connection timed out after 10 seconds of inactivity
Error: Failed to retrieve directory listing
The following are the most common issues with entering passive mode:
FTP Passive ports:
The above steps and other great information about passive FTP can be found here.