To actually use 100 Mbps upload, your TCP window must be calculated as:
If you are looking to "develop" or optimize speed for a system: Speed 100.100
iperf3 -c your_server_ip -P 4 -t 30 -b 100M -R # Download test iperf3 -c your_server_ip -P 4 -t 30 -b 100M # Upload test To actually use 100 Mbps upload, your TCP
If the result fluctuates more than ±1 Mbps, your bottleneck is CPU interrupt handling (Realtek NICs are infamous here). To actually use 100 Mbps upload