No WiFi Issue in iPhone 2G, 3G OS 3.0 Resolved

Besides the problem of batter, it seems that the Firmware 3.0 leads to a serious decline in the WiFi signal, which occurs both on and on 3GS iPhone 3G. No WiFi after upgrading iPhone OS3.0 Yesterday Apple updated their old article “Unable to use Wi-Fi or Bluetooth with iPhone or iPod touch because there’s no address listed for the device”.

Symptoms

* The device shows no Wi-Fi address or Bluetooth address (Tap Settings > General > About and scroll down to Wi-Fi Address or Bluetooth).
* iPhone or iPod touch appears to be connected to a Wi-Fi network but cannot use Wi-Fi for checking email, surfing the Internet, or other data transactions.
* iPhone or iPod touch showing Wi-Fi or Bluetooth icon on device as grayed out.
* iPhone not able to pair with Bluetooth device or accessory.
* When you tap Settings > Wi-Fi and then tap next to the network, no values or entries for IP Address, Subnet Mask, Router, or DNS appear.

Resolution

First, sync your iPhone or iPod touch to iTunes to backup your user information, Contacts, Calendar, and other data. Then try the following steps in order.

One : On the device, tap Settings > General > Reset > Reset Network Settings. Check to see if the device now displays the Wi-Fi address or Bluetooth address (tap Settings > General > About and scroll down to Wi-Fi Address or Bluetooth). If there is a Wi-Fi address and a Bluetooh address, then you’re done with these steps and you can resync your settings and your media using iTunes.

If there’s still no Wi-Fi address or Bluetooth address, then continue to step two.

Two :On the device, tap Settings > General > Reset > Erase All Content and Settings. Check to see if the device now displays the Wi-Fi address and Bluetooth address (tap Settings > General > About and scroll down to Wi-Fi Address or Bluetooth). If there is a Wi-Fi address and Bluetooth address, then you’re done with these steps and can resync your settings and your media using iTunes.

If there’s still no Wi-Fi address or Bluetooth address, then continue to step three.

Three :

1. Restore the iPhone or iPod touch software (this erases all data on the device) using iTunes.
2. After the restore is complete, sync your previous settings (mail settings, text messages, notes, call history, contact favorites, and so on).
3. Now see if your device shows a Wi-Fi address and Bluetooth address (tap Settings > General > About and scroll down to Wi-Fi Address or Bluetooth)

via apple support