WIFI Signal Degrades More Than You Think

Your high speed wireless network isn't running as fast as you think it is.

I recently went down the path of switching as many of my computers to gigabit ethernet and I wanted to test to make sure my cables were actually able to do 1000Mbit/sec. Unfortunately the normal route to do that is to buy a cable certifier unit that runs over $1000. But then I found iperf3, a linux/mac/win command line tool that can max out the network IO and tell you what it got.

That is when I realized it could give me actual wireless network speed instead of just transmitter rate. Now there are lots of potential bottlenecks with this setup — motherboard IO, NIC IO, my current radio airspace around my apartment, my router, etc. But it is interesting to see how a “realistic” apartment environment behaves with wireless signals.

Some notes of my setup:

  • The iperf3 server is running on an iMac that can local loopback 45000Mbit/sec (45Gbit/sec)
  • The iperf3 client is running on an Asus laptop that can local loopback 4300Mbit/sec (4Gbit/sec)
  • Over wired ethernet my router was able to switch 1000Mbit/sec between the laptop and desktop
  • My router is nothing impressive, it’s a D-Link DIR-860L running DD-WRT v24-sp2

You should not treat my results as a benchmark of all wireless setups but its interesting to see how it compares 2.4ghz wifi to 5ghz wifi at various channel widths.

2.4ghz Wifi N

  • advertised speeds are pretty unrealistic, according to my laptop and the router it is 144Mbps

5ghz Wifi AC

  • advertised speeds are pretty unrealistic
  • increasing channel width only helps nearby speed, far away spots will stay slow
  • going through 1 wall roughly cuts the speed in half




Want to run your own test?

You will need two computers – one to act as the server and one to act as the client.


iperf3 -s


iperf3 -c 192.168.0.x

I'm a 29 year old UIUC Computer Engineer building mobile apps, websites and hardware integrations with an interest in 3D printing, biotechnology and Arduinos.

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