Debugging my new network, when 10 Gigabit Ethernet Runs at 300 Megabits

The Intel E610-XT2 10 GbE card was limited to ~300 Mbps because its default receive buffers (512) caused massive packet discards, and Large Send Offload V2 for IPv4 throttled transmit throughput to ~313 Mbps. Raising the receive buffers to 4096 eliminated discards, and disabling IPv4 LSO boosted speeds from 313 Mbps to over 7 Gbps, restoring expected 10 GbE performance for SMB and iperf3 tests.