刚把相关设备升级到了 2.5G ，目前其他一切正常，唯独一台 iMac 下载速率不正常。

下载速率：

❯ iperf3 -c 192.168.11.11
Connecting to host 192.168.11.11, port 5201
[  5] local 192.168.11.129 port 50249 connected to 192.168.11.11 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec   131 MBytes  1.10 Gbits/sec
[  5]   1.00-2.00   sec   131 MBytes  1.10 Gbits/sec
[  5]   2.00-3.00   sec   131 MBytes  1.10 Gbits/sec
[  5]   3.00-4.00   sec   131 MBytes  1.10 Gbits/sec
[  5]   4.00-5.00   sec   134 MBytes  1.12 Gbits/sec
[  5]   5.00-6.00   sec   129 MBytes  1.08 Gbits/sec
[  5]   6.00-7.00   sec   130 MBytes  1.09 Gbits/sec
[  5]   7.00-8.00   sec   129 MBytes  1.09 Gbits/sec
[  5]   8.00-9.00   sec   133 MBytes  1.12 Gbits/sec
[  5]   9.00-10.00  sec   128 MBytes  1.08 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-10.00  sec  1.28 GBytes  1.10 Gbits/sec                  sender
[  5]   0.00-10.00  sec  1.28 GBytes  1.10 Gbits/sec                  receiver

上传速率：

❯ iperf3 -c 192.168.11.11 -R
Connecting to host 192.168.11.11, port 5201
Reverse mode, remote host 192.168.11.11 is sending
[  5] local 192.168.11.129 port 51966 connected to 192.168.11.11 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec   279 MBytes  2.34 Gbits/sec
[  5]   1.00-2.00   sec   280 MBytes  2.35 Gbits/sec
[  5]   2.00-3.00   sec   280 MBytes  2.35 Gbits/sec
[  5]   3.00-4.00   sec   280 MBytes  2.35 Gbits/sec
[  5]   4.00-5.00   sec   281 MBytes  2.35 Gbits/sec
[  5]   5.00-6.00   sec   280 MBytes  2.35 Gbits/sec
[  5]   6.00-7.00   sec   281 MBytes  2.35 Gbits/sec
[  5]   7.00-8.00   sec   280 MBytes  2.35 Gbits/sec
[  5]   8.00-9.00   sec   280 MBytes  2.35 Gbits/sec
[  5]   9.00-10.00  sec   280 MBytes  2.35 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  2.74 GBytes  2.35 Gbits/sec    0             sender
[  5]   0.00-10.00  sec  2.74 GBytes  2.35 Gbits/sec                  receiver

已经排查的点：

• 同一个端口同一个 USB 网卡，一台 Linux 是正常的，一台 M1 Mac Mini 是正常的。说明网线和 USB 网卡没问题，交换机没问题，iperf server 也没问题
• 手动下载 RTL8156 驱动并安装，并没有任何区别
• 关闭 iMac 上的 Surge 、iStat 等可能影响性能的软件，然而并没有用

请教一下大神，还有哪里可能有问题？我还可以怎么排查？

• 2.5G USB 网卡地址： https://item.jd.com/100023635636.html
• 驱动地址： https://www.realtek.com/en/component/zoo/category/network-interface-controllers-10-100-1000m-gigabit-ethernet-usb-3-0-software