[TCP Window Size in bits] / [Latency in seconds] = [Throughput in bits per second] The default window size that iPerf uses varies by machine type and operating system. I am new to Windows networking. Here is a calculator for getting the TCP window size. Thanks. So far Windows has gone through a long journey and has developed well. CTCP is available in Windows 8/10 and Server editions. In case of WAN connection, ACK is getting delayed from the server to the client because of latency in RTT of around 100ms. Client <<< From <<