Originally Posted by rockmyplimsoul
Check your router's settings, if you're hiding your SSID (network name) then for some reason iOS devices seem to lose track of the network. If that's the issue, you can un-hide the SSID since that is such a pitiful measure of security anyway.
If that's not it, what form of security are you using on your home network? If you're using WEP, try changing to WPA2 since (a) it is far more secure than WEP, and (b) Apple product seem to play better with WPA2.
Okay so I changed those settings, still no good. My phone will be sitting on my desk after I've selected the wifi and entered the password and I'll look over once in awhile and suddenly it's back on 3G. My roommates phone, also an iPhone 4 will always stay on the wifi when she's home. Same phones, same wifi signal, ??? Could it be a setting in the phone?