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1, 6, and 11 are the only non-overlapping channels. That's why you would use them the most. I'm not sure why the router would choose channel 2. Weird.

I'm pretty sure the channel change wouldn't...

This is what I use to check the wifi networks in the area:
http://www.nirsoft.net/utils/wifi_information_view.html

Did you check for other routers in the area? Maybe there is interference.

You'd normally use 1, 6, or 11 on 2.4GHz. I prefer to manually set the channel, rather than use auto.