Máy anh em thích thì tham khảo, do không đủ thời gian nên không dịch kịp: ............................................................... Problems reported after upgrading iOS 4.3.3 :- iPhone 4 says it connects to the Wi-Fi network, but the Wi-Fi icon never appears Wi-Fi keeps disconnecting and reconnecting on its own Can no longer use Wi-Fi at all unless within close proximity to the router Can't connect to Wi-Fi at all on device running 4.3.3, but devices running 4.3.1 have no trouble on same network Wi-Fi won't work, and resetting network settings doesn't fix Wi-Fi shows signal, but device can't connect to the Internet Basic Troubleshooting: Launch Settings app Tap Wi-Fi Turn Wi-Fi toggle off and then on again If this doesn't work then try to renew IP address, which may be required if you are using a larger wireless network. Renew IP Address: Launch Settings app Tap on the Wi-Fi network that you connect to from the list Scroll down and tap on the Renew Lease button If this doesn’t resolve the issue, try establishing a fresh connection with the Wi-Fi network by using the Forget This Network option. Please note that this will clear your current Wi-Fi network settings, including saved Wi-Fi passwords. Forget This Network: Launch Settings app Tap on the Wi-Fi network that you connect to from the list Tap on the Forget This Network button You will be prompted with a message that your iOS device will stop automatically joining this network. Tap on the Forget button. Go back to the list of Wi-Fi networks, try to locate and join the Wi-Fi network again. If this doesn’t help try restarting your iOS device. Restart iOS Device: Press and hold the Sleep/Wake button until "slide to power off" slider appears. Slide your finger across the slider and iOS device will turn off after a few moments. Turn iOS device on by pressing and holding the Sleep/Wake button until the Apple logo appears. If restarting your iOS device doesn’t resolve the problem then reset all network settings. Please note that this will clear your current cellular and Wi-Fi network settings, including saved networks, Wi-Fi passwords, and VPN settings. Reset Network Settings: Launch Settings app Tap General Scroll to the bottom of the screen and tap on Reset Tap Reset Network Settings When the device restarts, try to locate and join the Wi-Fi network again.