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Copying files from one computer to another across my home WiFi seems really slow.

My WiFi connection signal is decent, but the actual speed as reported by "Wireless Network Connection Status" seems to fluctuate between 9Mbps and 54 Mbps. But Windows Task Manager reports that regardless of my speed I am only using between 5% and 10% of whatever bandwidth is available at the time. I'm using a NetGear WRT54g with WPA.

Similar post here Why is my 802.11g wireless LAN so slow? suggests that 2MB/s (16Mbps) is about all I should be seeing with encryption enabled. But overall, I'm seeing an average of around 1.2Mbps (less than 10% of that!) with an average speed of 24Mbps, and one end is wired in my case.

There is no other traffic on my LAN, and the data is being copied TO a server connected to the access point via a 100Mbps connection. So I would assume that in this case I should be getting a lot higher transfer rate.

I should also add, that this slowness only seems to happen when copying files.

Update: It is slow copying with Windows Explorer. If I do the same identical copy from a command prompt it is at least twice as fast.

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For one thing, if both computers are connected by wireless, that immediately cuts the bandwidth in half as all data needs to be sent twice. It also adds a ton of overhead as the wireless link has to be "turned around" over and over. – David Schwartz Jan 12 '13 at 4:34
"There is no other traffic on my LAN, and the data is being copied TO a server connected to the access point via a 100Mbps connection". The 100Mbps is wired. – Michael Jan 12 '13 at 4:36
up vote 0 down vote accepted

I finally figured out the answer to my own question, quite by accident. Today I discovered that my server (that I was copying files to in this question) no longer could see the internet, even though all the machines going through the access point/router wirelessly could. After resetting the router the problem went away. A bit later I then did my daily copy to the server and found that it was taking 50% of the WiFi bandwidth.

So, if in doubt, reset the wireless access point/router!

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100 Mbps is the max theoretically possible, eh. I don't think it's realistically reachable in any remotely normal conditions. Also, there are things that slow transfers considerably. The router might be scanning files and such. The receiving computer might be having trouble treating the files and thus creating a bottleneck. Some security program might be slowing the process.

And uhm, try doing this through wired connection. Plug both computers through Ethernet cables to the router. If it goes faster, then you either just leave the problem aside and start using a cable for transfers, or acknowledge that Wi-Fi is the problem, not the network per se, and try to diagnose the issue more in-depth.

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