Struggling With Low Speeds < 15MBps Over Gigabit

StephenB wrote:
Testing with the broadcom part is also an important next step.

So, I disabled the Intel NIC and re-enable the Broadcom NIC

I'll add my network speed tests findings using the Broadcom NIC as I go, but so far the ping result was

C:\Users\XPS-8300>ping 192.168.1.2 -f -l 1403 Pinging 192.168.1.2 with 1403 bytes of data: Packet needs to be fragmented but DF set. x3 Ping statistics for 192.168.1.2: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), C:\Users\XPS-8300>ping 192.168.1.2 -f -l 1402 Pinging 192.168.1.2 with 1402 bytes of data: Reply from 192.168.1.2: bytes=1402 time<1ms TTL=64 x4 Ping statistics for 192.168.1.2: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms

As you can see, the pinging up to 1402 was was OK, but I got the 'Packet needs to be fragmented but DF set' message when I went above that figure.