A similar issue can be caused by misconfigured options or inappropriate configuration of your device's network settings. This is frequently the situation if your iPhone is suddenly unable to connect to Wi-Fi or is experiencing Wi-Fi issues after making some network settings adjustments. If you know which setting has changed and is causing you problems, consider reverting the changes to see if it solves the problem. If you still can't figure it out, you might want to try a network settings reset. Wi-Fi networks and passwords, cellular settings, VPN, and APN settings that you've used in the past will be erased, so make a note of them ahead of time. When you're ready, go through the following steps:
- From the Home screen, select Settings.
- Select General.
- Restart by pressing the Reset button.
- Select Reset Network Settings from the drop-down menu.
- Wait for your iPhone to remove all Wi-Fi networks and any other important data it has stored.
Reboot your device after the reset, set up your wireless network, and then try to reconnect. You'll have to reconnect to all of your Wi-Fi networks and re-enter their credentials.