Help: FIXED - Slow Wireless Internet vs. Fast Wired Internet

Discussion in 'Networking Issues' started by cgcatle, Feb 20, 2005.

  1. cgcatle

    cgcatle Network Guru Member

    I have a WRT54G v2.2 with 3.03.6 firmware. The problem is that my WIRELESS internet connection downstream data rate is about 1/2 of my WIRED internet connection data rate. The wired rate (to peaks at 6.6Mbps and averages about 5.5Mbps. The wireless rate peaks at 3.0Mbps and averages about 2.5Mbps (peaks measured by Netpersec tool). By comparison, the wireless rate for a local network file copy averages around 16Mbps, so the problem doesn't seem to be in the wireless link itself, but somewhere in the connection from the wireless access point in the WRT54G through the router portion of the WRT54G and out to the Internet.

    I've tried a number of things with no improvement so far, i.e. disabled encryption, turned off QOS, latest firmware, set to G-only mode.

    I would appreciate any advice from your network sages on how to correct this problem (presuming it is correctable!)

    P.S. I had very similar experience with a BEFW11S4 with internet wireless rates peaking at 2.5 and averaging about 2.0Mbps.
  2. Toxic

    Toxic Administrator Staff Member

  3. cgcatle

    cgcatle Network Guru Member

    I enabled "Frame Burst" with no improvement. The signal strength is "excellent" (10 feet from the antenna).

    Any other ideas? I presume the wireless internet data rate should be approximately the same as the wired internet data rate, assuming good signal strength. Is this presumtion correct?
  4. Esquire

    Esquire Mesquire Staff Member Member

    Not quite the same. The data packet carries a larger overhead with a wireless network so all things being equal you should see slower speeds over a wireless network compared with a wired counterpart.

    There are other factors affecting network speeds, and speed tests are often inaccurate, even when tested using the same server. Did you conduct the speed test for wired and wireless connection using the same computer?
  5. cgcatle

    cgcatle Network Guru Member

    I used the same computer (an IBM Thinkpad R40) for both wireless and wired internet connections to the same speed test server ( The results are very consistent over multiple tests with the wired connection averaging 5.5Mbps and the wireless connection averaging 2.5Mbps.

    The same wireless connection averages 16Mbps on drag and drop file copies over my local network. So, it appears the bottleneck is not in the wireless connection itself, but in some way the router is processing the wireless connection to the internet.

    I also see the same wired/wireless internet speed difference on two other computers on the network (all Win XP).

    Any ideas on solving this problem are MOST welcome!
  6. Esquire

    Esquire Mesquire Staff Member Member

    Have you tried assigning the same MTU value to each adapter?
    I use DrTCP to make changes rather than go through the registry. You need to manually assign the MTU value to each adapter. Reboot computer after saving changes.

    This may not have an affect, but are your wireless adapters drivers up-to-date?

    Have you also enabled Frame Burst in your adapter driver's properties?
  7. Esquire

    Esquire Mesquire Staff Member Member

    By the way, is your router new? Try taking it back to the shop for a replacement unit in case it is a dud.
  8. cgcatle

    cgcatle Network Guru Member


    I have found the fix to this problem. I had forgotten the "tcp receive window" size issue of yore (usually called RWIN). Win XP is supposed to dynamically manage this parameter to allow maximum performance, but in my case that did not happen for the wireless network adapter. My RWIN was sitting at 17520, which is too low for a 6Mbps internet connection with even average latency. I boosted it to 65700 and eventually to 131400 and am now seeing wireless internet download speeds equal to wired speeds. In my case both are averaging around 5.5Mbps with peak data rates of 6.6Mbps (the cable modem cap).

    Based on my experience, I suspect many folks with high bandwidth connections (>1.5Mbps) may not be getting the wireless performance they should.

    There are a number of sites with information on how to measure, optimize and set the RWIN parameter. Here are a few:;en-us;Q314053
  9. daggerNC

    daggerNC Network Guru Member

    cgcatle - THANKS!! I just bought a WRT54G router based on the recommendations of this and other forums primarily for the ethernet routing function, but my work laptop does have 802.11g so this was a bonus. I have the newest CDF9 v3.1 hardware using the 4.00.7 official Linksys firmware, so haven't figured out which enhanced firmware alternative to try yet.

    However, I'm using my laptop on the same desk as the router and was getting the same results as you- almost half the download thruput as when I use the wired ethernet connection. Finally found this thread and sure enough I see my RWIN is set to 17520. Setting it to 65535 via DRTCP and I'm now downloading @ 4.8M same as ethernet. Nice.

    Thanks again for posting your solution.

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