Network devices (30) receiving first packets from first devices (10) and in response transmitting second packets to second devices (20), and receiving third packets from the second devices (20) and in response transmitting fourth packets to the first devices (10), get manipulation means (40) for manipulating information at layers higher than internet protocol layers of headers of packets for improving transport efficiencies between the first and second devices (10,20). The higher layer may comprise a transport control protocol layer-4 to allow the network devices (30) to take over acknowledging functions of the second devices (20) and to take over re-transmission functions of the first devices (10) and to support the second devices (20) through offering additional buffer space and to support the first devices (10) through offering extended/advanced stream management.