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Slow internet connection on Wi-Fi PC.

Discussion in 'Wireless' started by Baba O'Riley, Jan 14, 2006.

  1. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    Hi guys and girls,

    I have a Belkin Wireless "Pre-N" MIMO Router and corresponding NIC hoked up to a 2Mbps ADSL connection. On my PCs that are wired into the router, when I run an internet speed test I regularly get 1500kbps or faster.

    Now, between a wired PC and the wireless PC, using Qcheck, I get a throughput speed of 35-40 Mbps (this is actual rather than the maximum connection speed reported in the System Tray - that's 108 Mbps). But when I run an internet speed test on the wireless PC, I only ever get a speed of 750 - 1000 kbps and I'm not sure why. I've fiddled about with the router settings - thought it might be to do with QoS being enabled but it doesn't seem to make any difference - so is this normal?

    If it's normal can someone explain why? If it's not normal, does anyone have any idea why the internet connection is so much slower on the wireless with so much spare available bandwidth?

    Cheers in advance.

    Baba :D
     
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  2. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    I've been wondering about this since I first saw the question, and I think I've come up with an answer.

    Wi-Fi imposes half-duplex on a link, moreover there are forced gaps between each packet.

    A packet from a remote site must go all the way to your machine before it can be ACKed. And of course the same for that ACK.

    This means that the usual system of full-duplex ACKs while receiving data won't happen.

    The actual speed will depend very much on what you are doing. Best test is to use ftp or similar to download a file. If you use a web-browser then that will be very chatty as it sends many requests for the various parts of a page, and I suspect will show a lower speed.

    Harry (waiting for his explaination to be torn to shreds!)
     
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  3. ffreeloader

    ffreeloader Terabyte Poster

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    Have you checked latencies on the wireless connection compared to the wired connections to see if there is a problem there?

    The things I would do are run pathping from both wired and the wireless PC's to the same sites to see what the latencies are. I'd also put a sniffer on the wireless PC to see if I was getting a lot of retransmits. That would point to packets being dropped by your router/switch.

    Have you checked the manufacturer's site to see if there are firmware upgrades for the router/switch?
     
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  4. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Um - you can toss my too-clever explaination in the bin! :oops:

    I set up a small lab to test it. I had a 20MB file on a server at work which I transferred with WinSCP3 to this machine, and put a copy on another server here at home.

    I then tested the speed downloading on my local net via 100Base-T, via ADSL (I have a 2Mbps connection) and then redid it after setting up an AP (Dlink DWL-2000AP+) and a cheap no-name USB WiFi client on my machine.

    Result - no material difference when using Wi-Fi via ADSL against using Ethernet - I got about 230KB/sec rate on both methods.

    So ffreeloader seems to have the edge in suggestions!

    Harry.
     
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  5. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    Thanks guys. Just to put another downer on your idea Harry, the router supports Burst Ack between it and the Wi-Fi client, I guess this is a way of making it a bit lighter on extrenuous packets. Although, to support your case, it does seem to be a bit faster downloading than browsing. When testing the connection speed, the worst results I get are on web based applications like www.pcpitstop.com and better results from applications like Nuria, that are desktop programs in their own right (and I guess use ftp).

    Freddy, thanks for the ideas, I'll have a fiddle as you suggest.

    Thanks again.
     
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  6. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    By the way, yes the router and NIC are fully up-to-date.

    Just tried pathping and the results are identical for each PC. I'll try a sniffer...
     
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  7. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    OK, I've just become an Ethereal noob. I'm not sure if I did this right. I started capturing packets, I then used the network connection a bit, moved a big file from one PC to the other and back, browsed the web, that kind of thing. I didn't see anything in the results that looked too out of place but like I say, I'm a noob. Also, I found the Analyze | Statistics dialogue and it said dropped packets were 0. I hope I'm interpreting that right! To make sure, I pingged the PC from a wired PC endlessy with different packet sizes and not one was dropped.
     
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  8. Neall

    Neall Byte Poster

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    It might be worth trying to get your hands on another wireless nic and seeing if you get the same performance.
    Then you can troubleshoot the software side of things after you have ruled that out.


    Neall
     
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  9. ffreeloader

    ffreeloader Terabyte Poster

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    I don't think that pinging from one of your wired PC's is going to show anything as I believe you said your only problem was from your wireless PC to the internet. Everything internal (your LAN) worked OK accorcing to your first post. You would have to ping from the wireless PC through your router to the internet to find any gotcha's related to internet traffic.

    Have you tried swapping out NIC's on the wireless PC and a wired PC to see if the problem follows the wireless connection from one PC to another?

    I kind of figured that you would find a higher latency through your router on the wireless connection to the internet than you do on your wired connections from the problem you described as the only symptom you have is from the wireless connection to the internet with LAN traffic being normal.
     
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  10. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    Not yet. What I might do first, as it's easier, is try wiring the wireless PC to the router as it has an ethernet socket on the mobo.

    Good point, from what I said about Ethereal though, am i barking up the right tree or am I doing completely the wrong thing with it?

    Thanks for the help.

    Baba
     
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  11. ffreeloader

    ffreeloader Terabyte Poster

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    Try doing a speed test from the internet and use ethereal to capture the download. See if it says no packets were dropped on one of those.

    Browsing the net itself doesn't take much sustained bandwidth so loading the connection may be the only time something shows up, if indeed the router is dropping some packets on the wireless internet connection.
     
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  12. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    OK Guys (especially Freddy),

    The Ethereal capture during a speed test suggests that it is having to rentransmit a lot of packets so there is the problem. To confirm, I tried the connection while it was wired to the router and it was fine.

    The Wi-Fi channel I'm using is fine (the router automatically selects the best available) but the Wi-Fi card has about 3 million other options to adjust, so I'm guessing one of these might be the problem. The trouble is, I don't know where to start... :oops:

    I might give Belkin customer support a call -24hr, freephone - the best customer support line I have ever rang :biggrin .

    Unless anyone got any more suggestions?

    Cheers!
     
    Certifications: A+, Network+
    WIP: 70-270

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