Incorrect settings or your router may cause fundamental problems. We also need to understand that Wi-Fi and the Internet are independent entities. Successfully connecting to a Wi-Fi router does not mean that you are connected to the Internet. Before continuing, try connecting your laptop to a mobile hotspot. If you have access to the Internet, the problem may be your Wi-Fi connection. If the problem persists, please continue reading.
1. restart MacBook and router.
2. Forget the Wi-Fi network and reconnect.
Three. Set the date, time and place
Four. Check for macOS updates
Verb (short for verb) changes DNS on Mac.
Intransitive verbs use MacBook wireless diagnostic tools
Seven. Disconnect the USB accessory.
Really can't. Let's find a professional technician to check and repair it.