Recently I bought a Google Pixel 3a phone. It worked nicely until I had to use the tethering feature (also called hotspot): it didn’t work at all.
Basically, this function allows you to use your phone as a WiFi hotspot to allow accessing the Internet from other devices (tablet, laptop and whatnot).
I tried replacing my SIM with ones of other operator and everything worked as expected. I then tried moving my SIM to other phones and it worked as well. The problem was definitely lying between my SIM and the Pixel.
I asked both Google and my mobile operator (that was an Italian MVNO called Tiscali) for support and, basically, they couldn’t help my in any way (so bad from them).
So I had no other option to switch to another provider: Ho Mobile. Ho Mobile is a MVNO operator operating in Italy as well.
With my great surprise, it didn’t work either.
So I basically started to search deeply on the interweb and found the solution.
Basically, you have to enable the developer mode and the USB debugging on your phone. To do that just follow one of the several guides on the internet (for example, this one)
Then you have to install ADB on your PC. You can find a nice tutorial for Linux, Mac OS and Windows here.
Now you should be able to run adb and connect to your phone.
Once you are connected, just type this command:
settings get global tether_dun_required
if it replies null or 1 you have to type this command
settings put global tether_dun_required 0
and you’re done! Just disconnect from the phone with this command.
exit
Now, if you followed your operator instructions for configuring the phone, the hotspot functionality should work as expected!