It sounds like you are unable to join the same Wi-Fi network that another device has no issue connecting to. I recommend starting with these troubleshooting steps from the article named:
iOS: Troubleshooting Wi-Fi networks and connections
- Restart your iOS device.
- Tap Settings > Wi-Fi and locate the Wi-Fi network to which you're connected.
- Tap and Forget this Network.
- Try to connect to your desired Wi-Fi network.
Note: You may need to enter your Wi-Fi password again if your network requires one.
- Turn your Wi-Fi router off and on2. If your ISP also provides cable or phone service, check with them before attempting this step to avoid interruption of service.
- Update your device to the latest version of software.
- Update your Wi-Fi router to the latest firmware2. For AirPort Base Stations, install updates using the AirPort Utility.
If this does not resolve the issue, try these steps from toward the bottom of the article:
- Verify that you're attempting to connect to your desired Wi-Fi network.
- Make sure you're entering your Wi-Fi password correctly. Passwords may be case sensitive and may contain numbers or special characters.
- Reset network settings by tapping Settings > General > Reset > Reset Network Settings. Note: This will reset all network settings including:
- previously connected Wi-Fi networks and passwords
- recently used Bluetooth accessories
- VPN and APN settings
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