LYE not working

Has this worked before? Or is this a new setup or new network connection?

Are other devices connected to the same network also (not) working?

Restart both your iMac and your router, and try again.

If that fails, here is what Apple recommends for troubleshooting a Wi-Fi network connection:

Manage the Wi-Fi connection on your Mac - Apple Support

If your Mac doesn't connect to the Internet over Wi-Fi - Apple Support

If you have a wired connection between your iMac and your router, the troubleshooting is slightly different.

Connect your Mac to the internet - Apple Support

Connect your Mac to the internet using Ethernet - Apple Support

Well, LTE is for mobile devices such as cell phones. Your Mac uses a wired internet connection.

so first, try this: https://www.businessinsider.com/why-wont-my-mac-connect-to-wifi