What does the 'SQL Server does not accept the connection error 10061' error code specifically indicate?

Error 10061, also known as 'Connection refused' (WSAECONNREFUSED), is a Winsock error, not an SQL Server error itself. It indicates that the client attempted to establish a connection to a specific IP address and port, but the target machine actively refused the connection. This typically means that there was no process listening on the specified port on the server, or a firewall on the server or network explicitly blocked the connection attempt, preventing SQL Server from even receiving and acknowledging the request.