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We have a 3Com OfficeConnect Wireless 11g Cable/DSL Router in our livingroom. It connects via ethernet cables to a server and a couple desktops, and via wi-fi to the Wii and a couple laptops (one running WinXP Home, the other Ubuntu 9.04).

The server and the desktops get their IP from the router using DHCP without problems.

The laptops and the Wii often end up requesting an IP 4-5 times before giving up. Sometimes it works if you just retry, other times it wont work for 10-15 minutes and then suddenly work, and some times it wont work at all until the router has been power-cycled (causing the server and the desktops to get disconnected from the internet).

Looking at the logs from the ubuntu laptop and the router, I can see that when it isn't working, the laptop sends a discover request, the router sees the request and issues an offer. The laptop sees no offer and sends a new discover, which the router replies to with a new offer. Repeat until the laptop gives up after a minute or so.

Since the router claims to be sending the offer, and the laptop doesn't see it, I was going to write it down as an ubuntu problem, until I realised the WinXP laptop had the same problem (although less often), and so does the Wii. I'm now wondering if it's a problem with the router, and if it's fixable or if I have to get a new one?

Other related information:

  • There are atleast 15 other wlans available in our apartment block
  • We use WPA encryption on the connection
  • There is no such problem when connecting to our neighbours unencrypted wlan (probably using a dlink router of some sort).
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closed as off topic by Tom O'Connor, Dave M, mdpc, Khaled, dunxd Feb 25 '13 at 11:37

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2 Answers 2

Sounds like packet loss (you say you are in an apartment with 15 other WLANs, and DHCP offers aren't being received by your workstations).

Try changing the wireless channel your 3com box uses. You might like to do a survey using Netstumbler or similar.

You could measure for packet loss using "mtr" on Ubuntu

Drop to the terminal and type

mtr [ip of 3com box]

If you don't have mtr installed, I believe you can get it by typing

sudo apt-get install mtr
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The router is set to select channel automatically, which I guess can explain why some times it works without problems, and other times it just doesn't work at all. I obviously can't run mtr when the problem is happening, as I don't have a net connection. Running it now, I have 0% loss, but I had no problem getting an IP today either, so... –  Epcylon Jun 12 '09 at 18:17
    
Try turning off automatic channel selection. –  tomfanning Jun 13 '09 at 9:14

Update with the latest firmware and try static DHCP assignment.

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