Interesting Problem

Discussion in 'Networking Issues' started by JamesPeters, Dec 9, 2005.

  1. JamesPeters

    JamesPeters Network Guru Member


    I've got an interesting problem. Up until 10 days ago, my WRT54G was working fine. Then it all changed. I noticed that whenever I went to download a large file (say over 5MB), the download would hang part way through.

    I reset all my network devices, tried a complete powerdown, bringing things up one at a time etc., but the problem persisted.

    Next I talked to my neighbours, and they are also having problems with their wireless networks - 2 x netgear, 1 x linksys, 1x belkin.

    So I fired up Net Stumbler, and looked at the connectivity / noise graphs. I noticed that all 5 of our networks become inaccessible for around 20 seconds every 1-3 minutes.

    Now I don't know enough to get any further than that, so I thought I'd ask if anyone else had ever seen any problem like this before?


  2. NateHoy

    NateHoy Network Guru Member

    Sounds like interference, like someone got a new 2.4GHz cordless phone that's poorly designed (spread spectrum), or some new device that uses the frequency for something else. 2.4GHz is an unlicensed band. It IS possible that someone put up a powerful WAP, one that does not broadcast SSID and perhaps is encrypted. Any new WiFi providers in your area, or is there a comms tower nearby?

    The only suggestion I have is to try different channels, and posibly increase your antenna strength to "drown out" the interference (of course, then you introduce more interference yourself), or get a grid to try and block the interference and make your WAP more directional to within your house/apartment.

    Without a field strength meter, about your only chance to figuring out direction is to take a piece of metal and hold it in various locations around your laptop and WAP to see if you can make the interference go away. If you can find out what direction the interference is coming from, you can try putting your WAP on that side of the house and putting up a metal grid behind it to help "shield" it from interference.
  3. JamesPeters

    JamesPeters Network Guru Member

    Update ...


    Just thought that I'd post an update. I updated the firmware on my router with the DD-WRT v23, then boosted the gain (xMit power) to around 150mW. This improved it (drowned out the noise?).

    I then slowly reduced it, and found around 90mW worked pretty well ... anything below 80mW and it was still cutting out.

    I also ordered the High Gain Antennas, and I have to say that since they arrived yesterday, the problem is 100% fixed!

  4. s1deout

    s1deout Network Guru Member

    I would try changing your channels as well. In 2.4Ghz there are only 3 non-overlapping channels.

    So if all of the AP's are on channel 6 (default for most of them) then that could be the issue as well. change to channel 1 or 11.
  5. ofbarea

    ofbarea Network Guru Member

    This entry in stumbler dot net FAQ from Fri 4 Feb 2005 will explain what was happening with your connection:
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