Something strange happed this evening. The wireless connection at home had such a bad signal quality that none of my devices could connect to the router.
At first, I did a router reset. Didn't help. Then I tried to reconnect the cables on the router, just in case. No success here also. Finally, I disabled all of the electronics around the router to make sure it wasn't an interference issue. This failed to solve the problem as well.
As I was troubleshooting the problem, I noticed a new wireless network scanned by laptop I had never seen before. It was broadcasting in the same channel with me (channel 11), and I was getting it with a signal quality comparable to that of mine. This seemed strange. Also the quality of my signal was fluctuating from medium to poor.
I looked it up online, and found that is possible for wireless networks to interfere with each other. I followed the suggestion in the article and changed my channel from automatic (resolved to 11 by the router) to 1. This did the job!
My router is Thomson tg585 v7.
Commands I used:
# sudo iwlist eth1 scan
Update 13 Nov 2010:
The same problem struck again. This time, I found it more convenient to do the scanning by using the "Wifi Analyzer" application, running on my Android Phone.