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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 192.168.1.7, 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?
Update
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.
drdrez
Posted 2013-09-29T17:25:46.490
Reputation: 177
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 – 2013-09-29T18:10:04.217
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 2Mto 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 – 2013-09-29T19:33:40.487@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 – 2013-09-29T19:41:58.243
@Spiff: Thanks for the suggestion! I updated my post with more information. – drdrez – 2013-09-29T23:39:54.490
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 – 2013-09-30T00:18:06.240
Well, first, that 450Mbit speed is based on optimal conditions for certain activities. But the real issue is likely to be the wireless adapter on the computer side. i.e. what good is a fast router if your computer can't connect to that standard? So are you even able to use 802.11n on the computer? ASUS states for performance: 802.11a : 6,9,12,18,24,36,48,54Mbps ///
802.11b : 1, 2, 5.5, 11Mbps ///
802.11g : 6,9,12,18,24,36,48,54Mbps ///
802.11n : up to 450Mbps. Sure looks to me like your wireless adapter is using 802.11g. – Debra – 2013-10-01T06:57:01.913
@Debra My card definitely supports 802.11n, http://www.newegg.com/Product/Product.aspx?Item=N82E16833704133 ; After testing with jperf (iperf GUI) and adjusting certain options (win sz, parallel strms...), I was able to get up to 94Mbit/s. The bottleneck must be the 100baseT on my server.
– drdrez – 2013-10-02T20:43:08.547