Mine is quite new. Android 9.0. The wifi can just about connect to my iPhone personal hotspot when you hold the phone close to it but even though the car is just outside my front room window it can't connect to my home wifi. My iPhone gets a pretty decent signal inside the car to the same wifi.No help, but I have the same issue. I've tried home wi-fi and my phone as a hotspot with no success. Sometimes you can find the apk of an app oniine, and save to and load from USB.
What Android version is yours, mine is 4.4 so is pretty laggy in the first place.
I managed to get an android phone to create a hotspot which was basically a repeater for my home wifi and that allowed me to download maps for sygic but ideally I'd like to be able to up the quality of the wifi on the device because then it might be able to get a solid connection to my iPhone for sygic traffic updates whilst driving etc.