If you can’t connect to a wireless network, and you know your userid and password are good, try powering down your device and robooting.
As a last resort, you can Reset your iOS device’s network settings:
- Tap Settings > General > Reset > Reset Network Settings
Note: This will also reset all your Wi-Fi networks and passwords, cellular settings, and VPN settings.
Reference: If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network: https://support.apple.com/en-ca/HT204051