Make sure that you are trying to connect to the correct network. Drag the status bar at the top of the display downwards (the bar you see your battery life and signal strength on). You should be able to see whether your Wi-Fi is turned on or not. If it’s not then turn it on. If your Wi-Fi will not switch on for whatever reason and remains “OFF” or not available then I suggest that you take your phone for a check up. If your Wi-Fi switches to the “ON” position and your cell phone just does not want to connect or stay connected to Wi-Fi then proceed with the advice listed below. If this setting is enabled then you’re probably having more problems than just no Wi-Fi connection, but still check this setting on the phone and make sure that Airplane Mode is NOT on.
Authentication issues are often (not always) a problem with the password. It tries to verify/authenticate the password that you are using to log into your router/network and if the password is wrong then it fails to authenticate and will show an Authentication failed error message. Following the first step in this article and triple checking the password can usually help to resolve authentication failed errors and allow you to get back on track and connected to your network once again. So quadruple check the password one more time just for good measure and make sure that it is 100% correct in every way.
Manually turn off the Wi-Fi and mobile data on your device, and then turn ON the airplane mode, while airplane mode is still active turn the Wi-Fi back on and then try to connect to the network again. Once the Wi-Fi is connected then you can turn airplane mode off. Don’t forget about the airplane mode though because if it remains on then your phone won’t receive calls or allow mobile data when you want to use it. This process sounds a little strange but this can sometimes solve this annoying authentication failed error message.
If the phone is not even locating possible Wi-Fi connections then make sure the Wi-Fi is actually working. If you have another phone or computer or any device that can see Wi-Fi connections make sure that the other devices can see and connect to it. If you have lots of connections to the Wi-Fi already then disconnect a few of them. Some wireless routers have a limit of how many devices you can connect to it. If the Wi-Fi network itself isn’t working than restart your router or modem. You shouldn’t need to press the reset button, just pull out the power cord from the router or modem, count to 15 sec, and then plug the power cable back in, wait a few minutes for the device to boot back up then try it again.
Starting to get tricky. For this issue chances are it’s your router or modem. Power cycle the router by unplugging for 15 sec and turn on again. If it’s still connecting but not using the internet then power cycle the phone itself, turn it off and then turn it back on.