As already stated, this error bubbles up from the TCP layer.  It means that the tcp stack, for example, gave up resending a tcp frame and timed out, determining that the recipient was no longer listening.
You cannot create this error yourself.  If you, for example, call s.shutdown(SHUT_WR), you get a WSAESHUTDOWN error.  If the connection is closed (via s.close()) you get a EBADF error.
Now, the interaction with the client may cause the client to misbehave, but this sort of error is usually either due to the network (other host becomes unreachable) or misconfiguration of the local host's tcp stack.