If you can't use your mobile phone as a Wi-Fi Hotspot, there may be several causes of the problem.
To use your mobile phone as a Wi-Fi Hotspot, you need to turn on Wi-Fi Hotspot and establish a connection from the other device to your mobile phone's Wi-Fi Hotspot.
Solution: Use mobile phone as Wi-Fi Hotspot
To use your mobile phone as a Wi-Fi Hotspot, you need to key in the password you selected when you set up your mobile phone as a Wi-Fi Hotspot on the other device.
Solution: Check the password for the Wi-Fi Hotspot on your mobile phone and key in the correct password on the other device.