If you are using the RTL8156, I think it has problems. Drivers or firmware, I don't know.Did more troubleshooting today. First iperf below is USB NIC through existing 1GbE network. 2nd one is USB NIC directly connected to 10GbE adapter in the server. If I set the USB NIC to a 1GbE link, I get the same huge number of retries. So this leads me to believe it is the Ipolex SFP+ module. Which sucks as I bought it from outside the country.
Code:PS E:\Downloads\iperf-3.1.3-win64> .\iperf3.exe -c 192.168.1.50 -P 2 -R Connecting to host 192.168.1.50, port 5201 Reverse mode, remote host 192.168.1.50 is sending [ 4] local 192.168.1.10 port 62766 connected to 192.168.1.50 port 5201 [ 6] local 192.168.1.10 port 62767 connected to 192.168.1.50 port 5201 [ ID] Interval Transfer Bandwidth Retr [ 4] 0.00-10.00 sec 565 MBytes 474 Mbits/sec 0 sender [ 4] 0.00-10.00 sec 564 MBytes 473 Mbits/sec receiver [ 6] 0.00-10.00 sec 569 MBytes 478 Mbits/sec 0 sender [ 6] 0.00-10.00 sec 568 MBytes 477 Mbits/sec receiver [SUM] 0.00-10.00 sec 1.11 GBytes 951 Mbits/sec 0 sender [SUM] 0.00-10.00 sec 1.11 GBytes 950 Mbits/sec receiver iperf Done. PS E:\Downloads\iperf-3.1.3-win64> .\iperf3.exe -c 192.168.1.50 -P 2 -R Connecting to host 192.168.1.50, port 5201 Reverse mode, remote host 192.168.1.50 is sending [ 4] local 192.168.1.10 port 62821 connected to 192.168.1.50 port 5201 [ 6] local 192.168.1.10 port 62822 connected to 192.168.1.50 port 5201 [ ID] Interval Transfer Bandwidth Retr [ 4] 0.00-10.00 sec 631 MBytes 529 Mbits/sec 20973 sender [ 4] 0.00-10.00 sec 631 MBytes 529 Mbits/sec receiver [ 6] 0.00-10.00 sec 787 MBytes 660 Mbits/sec 22268 sender [ 6] 0.00-10.00 sec 787 MBytes 660 Mbits/sec receiver [SUM] 0.00-10.00 sec 1.38 GBytes 1.19 Gbits/sec 43241 sender [SUM] 0.00-10.00 sec 1.38 GBytes 1.19 Gbits/sec receiver iperf Done.
Is it the Cable Creation model you have ? Even if it worked, it is really not well made.
The USB cord is too short. When using it with a desktop, it hangs from the USB 3 ports and loses the USB connection under the weight of the heavy CAT6A STP cable I used ... It needs a short USB extension cord. Sigh. Or maybe if I find an old PCIe USB 3.0 controller card in a drawer, put it at the bottom slot, that'll solve the problem ...
Anyway, the RTL8156 has problems even with my Trendnet 7080-ES NBASE-T switch. See http://blog.madbrain.com/2020/06/realtek-rtl-8156-usb-25-gbps-ethernet.html . Seems like the chip you are using also has incompatibilities with your SFP+.