1.Make sure your router is on and that you're within rangeIf you're too far from your router you won't get a signal, so make sure you're within range.
Tap Settings > Wi-Fi and make sure Wi-Fi is turned on. Tap the name of your Wi-Fi network to join. A blue checkmark beside a network name means you're connected. Or get help if you can't turn on Wi-Fi.
2.Make sure Wi-Fi is on and that you can see your network
If prompted, enter the password for your Wi-Fi network. Learn what to do if you don’t know your password.
3.If prompted, type in your Wi-Fi password
If you still can’t connect to your network or get online, make sure your router is connected to the modem and turned on.
4.Check all of your cables and connections.
For more help, try restarting your device, router, or cable/DSL modem. After each step, check to see if you fixed the issue.
• Restart your iOS device.
• Unplug your router and plug it back in.
• Unplug your cable or DSL modem and plug it back in.
6.Still can’t connect?Reset your Network Settings. Tap Settings > General > Reset > Reset Network Settings. This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you’ve used before.
Get more help
1) If someone else set up your network, ask them for help. If you’re using a network at a company, school, hotel, store, or other free Wi-Fi location, find an employee for assistance.
2) If you're connected to a Wi-Fi network but you can’t get online, try to use your Wi-Fi network on other devices. If you can’t get online using your other devices, there might be a service outage. Call your cable company or internet provider for help.
3) Try connecting to a Wi-Fi network in a different location. If your device can connect, you’ll need to get help with your Wi-Fi network. If it can’t connect to any Wi-Fi networks, contact Apple.
4) Update your Wi-Fi router with the latest firmware and make sure the router supports your Apple product. For more information, contact the manufacturer of your router.
Hope one of the ways can help you fix the iPhone won't Connect to the wifi problem.