If your iPhone can recognize the network but cannot join it, then confirm whether other devices on this network can connect normally to determine the validity of the wireless, such as no problem with the wireless:
1. Turn off and open the wireless switch again;
2, restart your device;
3, Settings - general - restore network Settings;
4, Settings - General - Restore all Settings. If other devices cannot connect to the wireless network at the same time, please restart your router; 2, replace other wireless network test.