Is the NIC connected over USB?

[ak_hepcat]

Multiple send/receive threads are the best way to test your network.

netperf can do this, but it's not very friendly.

https://github.com/akhepcat/BettererSpeedTest

It's just a fork of somebody else's "BetterSpeedTest" script, but with some additional options for bigger (1Gb) pipes
and cleaner reporting (for embedded scripting)

Using 20 threads I can get 940Mb/s DL and 480Mb/s UL - on a symmetric 1G direct-internet connection (it's good to work for a large ISP)