HOW TO CONNECT IPHONE 4 ON WIFI

Hi munashefromchecheche,

Before trying anything else, please ensure that the network that you're trying to connect to is a 2.4GHz band. The iPhone 4 did not ship with support for 5GHz band connections.

If the device you're trying to connect to is a 2.4GHz connection, and you're still not able to connect, try the options below, checking after each one if you're able to connect. I'll be using this guide to direct you: If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support

1. Make sure that the router is on, and you're within range;
2. Make sure that Wi-Fi is on and you can see your network (Tap Settings > Wi-Fi and make sure that Wi-Fi is on);
3. Check your cables and connections (This means checking the cables connected to the router);
4. Try restarting your iPhone;
5. Reset your network settings. (Tap Settings > General > Reset > Reset Network Settings. This also resets Wi-Fi networks and passwords, and VPN and APN settings that you've used before);

If you still cant connect to your Wi-Fi, you may need some more help. Try these if that is the case:

• 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.
• 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.
• Try connecting to a Wi-Fi network in a different location. If your device can connect, you need to get help with your Wi-Fi network. If your device can’t connect to any Wi-Fi networks, contact Apple.
• Update your Wi-Fi router with the latest firmware and make sure that the router supports your Apple product. For more information, contact the router's manufacturer.

If you have any further questions, queries or concerns, please don't hesitate to reply to the thread as I'm following it.

Best of luck!