I just replace my old router with an ASUS RT-N66U. The router says it supports up to 450Mbit/s on 2.4GHz and 5GHz. I know I cannot expect to exactly reach that speed because of overhead and interference, but I am not getting speeds even remotely close to that.

My computer has a TP-LINK TL-WDN4800 PCIe adapter which I bought in the past few months. I used the program iperf as suggested by some other posts on superuser. On my PC, I run the command iperf -c, and on an old headless PC connected to the router via ethernet, I ran iperf -s.

After doing a couple of runs, I get anywhere between 40Mbit/s and 50Mbit/s. I have a long ethernet cord that I used to connect my PC and router, and did the same test again. I got a solid 94.1Mbit/s to my headless PC.

I haven't seen any examples of what speeds other people get on their home networks. However, I feel like both the wireless and the wired speeds to my server are really slow. Is it possible I got a bad router? Is some other factor causing both tests to run slow? What can I do to find the cause of the slow speeds and fix it?


As suggested in the comments by Spiff, I was able to determine the speed of my headless PC's built-in ethernet port. It is running Ubuntu server, and after installing the package I used the command ethtool eth0, and determined that the max speed it supports is 100Mbit/s (the 100baseT/Half 100baseT/Full standards). My PC with the wireless adapter supports 1000baseT/Half 1000baseT/Full.

I can't say I am surprised about the server, it is a VERY old computer. So I should probably purchase a PCI/PCIe gigabit ethernet port. However, that doesn't explain why the wireless speeds are so low.

I will update this post when I find a system with a gigabit ethernet port to test iperf with.

  • When it comes to wireless, there are so many different factors and variables, that there is no way to point to something as a culprit. – Keltari Sep 29 '13 at 18:10
  • First figure out why you weren't getting gigabit speeds in the wired Ethernet case. Do both PC's have gigabit Ethernet cards? Do you have properly wired Cat5 or better cables? Try adding -w 2M to both IPerfs to set the TCP window size nice and big just in case. You should be getting in the high 930's of megabits per second. 941 is about the theoretical max. – Spiff Sep 29 '13 at 19:33
  • @keltari Guys like me—that know about wireless—actually can and do routinely help people diagnose, understand, and fix wireless performance problems. It's a bummer that not everyone has a spectrum analyzer, but that doesn't mean that all problems must just be shrugged off. – Spiff Sep 29 '13 at 19:41
  • @Spiff: Thanks for the suggestion! I updated my post with more information. – drdrez Sep 29 '13 at 23:39
  • Beware that adding a GigE NIC to a very old PC might not get you full gigabit speeds. And unless your NIC does a great job of interrupt coalescing, the number of interrupts per second that a busy GigE NIC can generate can swamp an older CPU. – Spiff Sep 30 '13 at 0:18

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