Use Service to identify the use of the connection. Windows provides There are a number of standard service names such as ftp, http, finger, and time. Servers can specify additional services and their associated ports in a SERVICES file. For more information, see the Microsoft documentation for Windows sockets.  

Certain port numbers are reserved for specific values of service. Thus, Service provides a more meaningful way to specify the server Port to use for the socket connection. For server sockets, using Service rather than Port ensures that the server will listen for TCP/IP requests on the appropriate port.

ESocketError 

Port 

SetService 

LookupService