Cannot connect to FTP server using FileZilla 3.10 (or higher) client. The connection fails by timeout.
Error: The data connection could not be established: ETIMEDOUT - Connection attempt timed out Error: Connection timed out Error: Failed to retrieve directory listing
Status: Insecure server, it does not support FTP over TLS. Command: USER user Error: Connection timed out after 20 seconds of inactivity Error: Could not connect to server Status: Waiting to retry...
NOTE: The content of error messages might be different depending on the version of FileZilla.
This issue is related to FileZilla version.
Starting with 3.10.0, FileZilla uses "FTP over TLS" mode by default. According to FileZilla release notes:
FTP over TLS is now used by default if the server supports it. Use of plain FTP can be enforced for a server in the Site Manager.
Connection fails if "FTP over TLS" is not accepted by server.
In the connection settings of FileZilla (File > Site Manager > Site_Name > Encryption) choose the appropriate mode the FTP server is working in.