How to fix iPhone WiFi connectivity issues?

You can typically fix an iPhone that won’t work after following a few simple troubleshooting steps.
connect to wifi.
Initially, you can just make sure that:

• The WiFi is activated.
• The airplane mode has been disabled.
• The WiFi password is typed in correctly.
• The technology is current.

If you are certain of all the aforementioned ways try restarting your device and resetting the
network settings.
If you still are unable to connect to wi-fi you might need to factory reset your device, before
you do this make sure to back up all your data as it will erase the data from your device.
To do this you need to follow these steps:

Settings> General > Reset> Erase all content and settings.

Your device will now be as fresh as new and you can restore the data from the backup
created.