Top Features of ArGoSoft FTP Server .NET for Windows Developers

Troubleshooting Common Issues with ArGoSoft FTP Server .NET

1. Connection failures

• Check ports: Ensure port 21 (control) and port 20 (data for active mode) are open. If using passive (PASV), configure a passive port range in ArGoSoft and open/forward that range on firewall/NAT.
• Switch mode: Try Passive vs Active in the client—passive usually works behind NAT/firewalls.
• IP binding: If server is behind NAT, set the external IP for passive responses or use a hostname that resolves to the public IP.

2. “Can’t open data connection” / PASV errors

• Passive port range: Configure and open the passive port range on server firewall and router.
• Server PASV reply IP: Ensure PASV returns the public IP (not a private LAN IP) or clients will fail to connect.
• Firewall inspection: Disable/adjust FTP inspection features in gateways that may rewrite FTP control/data.

3. Intermittent or partial transfers

• Timeouts: Increase client and server timeouts. Large transfers may need longer timeouts.
• Antivirus/scanner: Temporarily disable real-time scanning to test; some scanners corrupt transfers.
• Keep-alive: Enable TCP keep-alive or reduce long idle periods during transfers.

4. Authentication and permission errors (e.g., 530 / 550)

• Credentials: Verify username/password and account enabled in ArGoSoft.
• Home directory & rights: Confirm user’s home directory exists and NTFS permissions grant read/write as needed.
• Account restrictions: Check quotas, concurrent-session limits, and IP restrictions in server settings.

5. Directory listing problems

• LIST command compatibility: Some clients expect different LIST formats—try switching client settings or use a simple LIST command.
• Encoding/locale: Ensure server and client use compatible encodings if filenames appear garbled.
• Large directories: If listing times out, increase data timeout or page directory contents (client-side) where possible.

6. TLS/FTPS or SFTP problems

• Protocol support: Confirm ArGoSoft supports FTPS or SFTP as required; mismatch causes failures.
• Certificates: For FTPS, install a valid certificate and ensure the server presents the correct cert chain.
• Port and mode: FTPS often uses different ports; adjust firewall and passive settings accordingly.

7. Firewall, NAT, and router troubleshooting checklist

• Open ports: 21 (control), 20 (active data), passive range (configured).
• Forward ports to server’s LAN IP.
• Configure server to advertise external/public IP in PASV responses.
• Temporarily disable Windows Firewall/third-party firewall to isolate cause.

8. Logs and diagnostics

• Enable protocol/debug logs in ArGoSoft and examine client/server exchange for error codes (e.g., 425, 421, 550).
• Reproduce with multiple clients (FileZilla, WinSCP, curl) to isolate client-specific behavior.
• Packet capture (Wireshark) for passive-mode PASV replies and failed data connections.

9. Common error codes and quick fixes

• 425 Can’t open data connection: Passive port range not open or PASV IP incorrect.
• 530 Not logged in: Bad credentials, disabled account, or home directory problem.
• 550 Permission denied: NTFS permissions or wrong working directory for the FTP user.
• ECONNREFUSED / Connection refused: Server not listening on expected port or firewall blocking.

10. When to update or contact support

• Update ArGoSoft to latest version if bugs suspected.
• Contact ArGoSoft support with protocol logs, configuration (passive range, advertised IP), and examples of failing client sessions.

If you want, I can produce a concise step-by-step checklist tailored to a Windows server setup (firewall rules, router port-forwarding, ArGoSoft passive settings).