In my opinion try the following..
1. Restart and turn off battery saving mode if its on.
2.Adjust your Wi-Fi settings.. putting your phone in Airplane mode for a brief time will turn off Wi-Fi and mobile data, which can help reset your network and solve the issue.
3.Check if your software is UpToDate
4. Lower the frequency band on your phone newer phones can transmit data faster over a Wi-Fi network because they use a 5 GHz frequency band. But if the device you’re trying to connect with doesn’t support this frequency, you may need to switch to a lower one (like 2.4 GHz) for your phone’s mobile hotspot to work successfully.
5. Reset your network settings when your mobile hotspot won’t work, resetting your network settings may be your only option. This only clears your Wi-Fi passwords and saved networks—it doesn’t delete any other data.
