I have faced the problem of my Xiaomi phone wifi not connecting to saved hotspot. Mostly my home hotspot, but it has happened with others as well.
How to change the hotspot name of your iDevice. This simple and easy tutorial shows you how to change your Apple iPhone’s personal hotspot name to make it easier to identify and connect to.
Somewhere along the line, someone will attempt to sell this “universal wireless wifi” to you. It may be a roadside hawker at Computer Village, Ikeja.