Cannot connect to internet using wifi

About a week ago my MacBook stopped using wifi to connect to the internet. It connects to wifi no problem. I can plug in a USB 4G stick to connect to the internet no problem. My TV uses wifi to connect to the internet no problem. So the issue has to be a software problem on my MacBook which is specific to connecting to the internet over wifi.

I have a MacBook Pro Retina, 13 inch, mid-2014 running BigSur 11.6.1.

I have tried safe mode - no change.

I have tried re-installing Big Sur - no change.

Any suggestions?