TCP Provider: No connection could be made because the target machine actively refused it

This error is a network-related error occurred while establishing a connection to the Server. It means that the error is occurring because there is no server listening at the hostname and port you assigned. It literally means that the machine exists but that it has no services listening on the specified port . So, http://csharp.net-informations.com/communications/connection.htm can be established.

Try running netstat -anb from the command line to see if there’s anything listening on the port you were entered. If you get nothing, try changing your port number and see if that works for you. In Windows operating systems, you can use the netstat services via the command line (cmd.exe) . On Linux you may need to do netstat -anp instead.

The target machine actively refused it occasionally , it is likely because the server has a full ‘backlog’ . Regardless of whether you can increase the server backlog , you do need retry logic in your client code, sometimes it cope with this issue; as even with a long backlog the server might be receiving lots of other requests on that port at that time.