your Wi-Fi reverts to Edge? READ THIS
There are multiple choices for the encryption method (for secured wireless networks) on the IPhone. The IPHONE default is "WEP-Passphrase" (example "yourdogsname").
If you are setting up the network and it appears to connect but you get an IP address that is like "16x.x.x.x" instead of the usual 192.x.x.x the IPhone is not properly logging onto your network.
Instead of simply entering your Wi-Fi key into the "security" field on the wi-fi setting screen. CLICK ON THE SECURITY FIELD and you will then be given a list of choices that includes things such as "WEP-HEX OR ASCII KEY"
If your wireless key is something like "A5D123456" then you have a HEX KEY not a PASSPHRASE. Conversely if you have "dogsname" as a wireless key then it is a passphrase not a Hex Key. Ensuring that this setting is correct will solve most peoples connection problems.
I am an IT professional and it took me an hour to figure out this rediculously simple fix.
PC, Windows XP