I have a customer with a Linksys WRT54G router. The Wi-Fi was configured for Ch 1. The iPhone and iPad have always worked on Wi-Fi. Suddenly the phone and iPads were losing Wi-Fi connectivity. So I assumed router bad. Replaced with a Linksys E1000. Configured same - would not work (would connect to wireless, but speedtest.net would only give 0.01 Mbps.
As soon as I change to Ch 11, speetest slams to 5Mbps. Change back to Ch 1, 0.01 Mbps, back to Ch 11, 5 Mbps.