I used to only get 2-3 mbps in game until I discovered my ISP was screwin me. A few phone calls and holding a cable tech hostage for 20 hours uncovered they we’re throttling the connection. It seems all that traffic (50-80mbps) was caught by network engineer geeks and deemed to be a possible illegal download of material. Since then it has been corrected and all is good with the world.
On a side note, windows does not like certain versions of the Intel Ethernet Card, and the win driver can cause similar issues. I ended up getting a vendor driver which fixed that problem months ago.