When tcpip.sys has received data it call Receive Handler for endpoint (if it has set). If your driver regsiter such handler, th must retrieve data (it should setup IRP for last parameter of the handler). If your driver is not interested in the incoming data, it set this irp = 0. Tcpip after seeing this irp = 0 thinks client dont need this data and dont take any action for saving data. So, exsiting client with registered ReceiveHandler which always return irp = 0 way to loose all incoming data for endpoint.
