"Connection terminated after XX seconds of inactivity" error in FileZilla

Sometimes when working with FTP, errors like:

Status: Connecting to XXX.XXX.XXX.XXX:21 ... Error: Connection interrupted after 20 seconds of inactivity Error: Unable to connect to the server

Such errors indicate that the connection to the server failed. The reasons for this problem may be:

  • Server unavailability.
  • Problem with one of the nodes on the route to the server.
  • Closed FTP port (port 21 is used by default).
  • One of the ports allocated by FTP on connection is closed.
  • Using FTP+SSL (FTPS/Implicit FTP).
  • Active transmission mode.

To diagnose the problem, you need:

  • Run a trace. To do this, use instruction. If there is a problem during the trace phase, then you may want to contact your ISP to check for an address availability issue.
  • Check port availability. Connect to the server with telnet port 21 (or the port used by the FTP server). If the connection fails, you should contact your network administrator or ISP to check for a port availability issue.
  • Check if an IP address is blocked by DDoS protection. If there is a problem at the trace stage, then checkwhether your IP address is blocked by DDoS protection.
  • Check the set encryption method. If FTPS (Implicit FTP) is set, change it to FTPES (Explicit FTP) or regular FTP without encryption... It is recommended to use «Explicit FTP over TLS if available».
  • Check transfer mode. Please note that if you are behind a NAT or Firewall with rules for filtering incoming requests on potential FTP ports, you should use passive mode.

If the actions described above did not help in solving the problem and finding its causes, then you need to:

  • Clarify your IP address. (For example, this can be done on the website 2ip.ua).
  • Repeat the above steps and save their results as text or screenshots.
  • Contact us at technical support and provide the obtained data for additional verification of the problem.