I must say that in 2.5 years, and countless wifi installations, I’ve never encountered a problem with interference on wireless LAN channels.

But in this case, it seems highly likely.

Customer had a wireless router, and the wireless part of the router stopped working. So I install a new belkin wireless router, and everything seemed to work well (with the one wireless desktop PC).

A few days later, he asked that I setup 2 laptops for the 802.11 wireless network. One laptop (IBM thinkpad) cannot be setup (it sees the wireless network, but the 802.11B card in the laptop doesn’t support the WPA protocol (only WEP, which I wouldn’t use nowadays).

The other laptop (Acer) has builtin 802.11G electronics, so it should be easy.

But it cannot see any wireless networks within range… despite the other thinkpad seeing the router via the 802.11B network…

I check the desktop PC that I setup a few days ago, and it seems to have suddenly lost its connection (despite it saying that it is connected, I cannot ping the router…)

I connect to the router via an ethernet cable, and everything looks fine…

I decide to change channels (from channel 13 to channel 3… you can see I’m a lazy typist  🙂 )

Customer also says that he has 3 different wireless/cordless phone systems in the house (attached to the landline). And he says the dropouts happen less frequently in the late evening.

So I’m starting to suspect a channel overlap problem. The channel change should fix things.

But I also show the customer how to change the router channel, so he can experiment if need be… If it becomes an ongoing issue, I might need to explain that the channels actually overlap, such that channel 1 can also see the signals from channels 2, 3, and 4.

Ideally (to minimise overlap with many routers close together), I’d say the channels to select are: 1, 5, 9, 13 (only if you select the Australian wireless range… other countries might only have channels 1-11, in which case, just use channels 1,5,9).