In case of named pipe connection, if named pipe handle is bound to IO completion port, connector's overlapped read and write operations would cause completion notification sent on that port.
This is not intended. async IO inside the client is only a trick to support IO timeouts.
In the server's VIO, it is already handled properly, completion notification are prevented In connector, it should be done exactly like that, it is not entirely clear why it was lost when copying the server's logic.