Help person

Try to go to apple diagnostics, and see if it detects any problem with the wifi. Click on the link to see how to Use Apple Diagnostics to test your Mac. Make sure you also click on the link inside the link about the reference codes as well. They say what the code means.

But first....make sure it's not the router or the modem's fault, and see if the other devices can connect to wifi. Do the diagnostics if the MacBook is the only one that can't connect to wifi.