If you are using Windows as your operating system, want to transfer many files via FTP and experience connection failures with explicit encryption (FTPS), then the Windows firewall on your local PC may be the reason for the problem.

To fix this, stateful FTP filtering can be disabled.

Proceed as follows:

1. Start the Windows command prompt (cmd) as administrator.

2. Enter the following line:

netsh advfirewall set global StatefulFTP disable

3. Confirm the input and execution with the Enter key.

If you want to re-enable stateful FTP filtering, you can proceed as described above, but use the following line:

netsh advfirewall set global StatefulFTP enable