Before I moved onto an iphone data plan, i didn't use 3G, and my Wi Fi was perfect. Yesterday, I used 3G and wifi, it was perfect. Today, Wi Fi not working. my iphone keeps reverting back to 3G when I have activitated WI FI when surfing websites. I have looked at Apple support site and addressed the issues there, but nothing solved. "If you're trying to connect to Wi-Fi and it looks like you're connected, but when you access a web page, it goes back to the cellular data network it may be due to a known issue if the wireless router is using MAC Address Filtering and the iPhone MAC address has not been entered into the filter list. This may also occur if the WEP password was entered incorrectly." NO. WPA-PSK entered correctly. NO MAC Address filtering active on my wireless modem. I have tapped Forget this Network millions of time. I don't want to turn off WPA-PSK encryption on wireless router I do not have WEP encryption on the wireless router. I have resetted Iphone network. I have tapped renew lease. I am still surfing on 3G when I have Wi FI activated...help please!! I tried to deactive 3G by putting a 1 next to 3services in the APN section (cellular network) on iphone, so i can just use wifi purely. But now, my wifi is not working at all!