# iperf 2.0.5 on Windows 7: degraded/inaccurate throughput

Was testing out some wireless equipment today using iperf on (at first) two Windows XP workstations. Throughput testing was fairly consistent at around 18Mbps.

Moved equipment around (outside), tested again this time with a Windows 7 laptop and one of the XP machines again and throughput dropped to ~4Mbps. Thinking that I somehow had incorrect gain settings, poor LoS, etc., I changed configuration several times but to no avail.

Brought the gear back indoors and setup the antennas exactly as they had been with my original XP-to-XP iperf tests, reverted the configuration to as it was, but still using the laptop as the iperf server (-s) and again, ~4Mbps throughput.

As a sanity check, I plugged the patch cable into the second XP workstation as I had originally tested it and voila: 18Mbps avg. throughput.

My question is: is this a known issue with iperf 2.0.5 on Windows 7 (compiled using cygwin) or is there something on Windows 7 as far as network settings that I should be looking at? Windows 7 laptop is a higher-end Dell laptop; only a few months old. Not sure of the NIC manufacturer at this point so could be Intel or Broadcom I imagine (the latter may be the culprit?).