FileZilla Passive Mode Port Range Behavior When Server Firewall Restricts High Ports

When configuring FileZilla for FTP transfers, the goal is to achieve reliable passive mode connections in both local and production environments.

The client’s passive mode defaults to requesting a random port in the full 1024‑65535 range, which works locally where outbound traffic is unrestricted. In production, firewalls often block those high ports, causing transfers to stall even though the client appears correctly configured. FileZilla permits a custom passive port range to be set, but the documentation does not state whether the client will automatically limit its requests to the range that the server firewall allows, leaving the alignment decision unclear.

Does FileZilla automatically adjust its passive port requests to match the server‑allowed range when a custom range is configured? If not, what steps should be taken to confirm that the client‑specified range aligns with the server firewall settings before moving to production?