That's not right. There could be a hardware fault, and it may be simple to fix. If that's the case though, only Apple or an authorized Apple Repair facility can fix it.
First read and follow If your Mac doesn't connect to the Internet over Wi-Fi - Apple Support, then Contact Apple Support.
After performing all the usual perfunctory steps, (update macOS, check your router's firmware, etc) the Apple Support representative will probably refer you to that document. Assuming they do, you can tell them you already did that. Then, ask if they want you to forward its report to them.
Let me know what happens.