Debugging my new network, when 10 Gigabit Ethernet Runs at 300 Megabits
Summary
Post documents a real-world home network troubleshooting case where 10 GbE throughput was limited by NIC offload behavior. Through testing with iperf3, iostat, and Windows NIC settings, the author demonstrates how increasing NIC receive buffers and disabling LSO V2 for IPv4 dramatically improved sustained throughput. The piece advises measurement before changing configurations and highlights how a single NIC setting can unlock several gigabits of performance.