Users are unable to connect using SFTP.

If users are unable to connect using SFTP (Secure File Transfer Protocol), it can be caused by various issues. Here are steps to troubleshoot and resolve the problem:

1. Check SFTP Server Status:
   • Verify that the SFTP server is up and running. Check for any maintenance or outage notifications from the server administrator.
2. Verify SFTP Server Configuration:
   • Confirm that the SFTP server is properly configured to accept connections. Check settings like port number, authentication methods, and user permissions.
3. Firewall and Network Configuration:
   • Ensure that the firewall on the server allows inbound connections on the SFTP port (default is 22). Additionally, check network configurations for any potential issues.
4. Verify SFTP Username and Password:
   • Double-check the username and password being used for authentication. Make sure they are correct and haven't been changed.
5. Test Connection with Different SFTP Clients:
   • Attempt to connect using a different SFTP client to determine if the issue is specific to one client application.
6. Check SFTP Server Logs:
   • Review the server logs for any error messages or indications of why the connection is failing. This can provide valuable information about the issue.
7. Verify Correct Protocol and Port:
   • Ensure that users are attempting to connect using the correct protocol (SFTP) and the correct port number (usually 22 for SFTP).
8. Check for SSH Key Authentication:
   • If users are using SSH key authentication, ensure that the public key is properly installed on the server for the respective user.
9. Check User Permissions:
   • Verify that the user attempting to connect has the necessary permissions to access the server via SFTP. Check both user-level and system-level permissions.
10. Check for IP Whitelisting or Blacklisting:
    • Verify if there are any IP whitelisting or blacklisting rules in place on the server that might be preventing the connection.
11. Test on a Different Network:
    • Attempt to connect from a different network to see if the issue is related to the user's local network configuration.
12. Check for Server Capacity and Load:
    • Verify that the server is not overloaded with too many concurrent connections. This could potentially lead to connection issues.
13. Verify SFTP Subsystem Configuration:
    • Check if the SSH server configuration file includes the SFTP subsystem and that it is configured correctly.
14. Restart SFTP Server:
    • If possible, try restarting the SFTP server to see if it resolves the issue. This can sometimes clear out any temporary glitches.
15. Consult Server Administrator or Support:
    • If none of the above steps resolve the issue, consult with the server administrator or contact support for further assistance.

By following these steps, you should be able to identify and resolve the issue preventing users from connecting via SFTP.