You have two types of Internet connection. One is while driving, and uses a cellular 4G (maybe a 3G connection on a 2017 Tesla?) connection with AT&T that Tesla provides. The other is a WiFi connection that you configure, generally at home and maybe at work, that attaches to the Internet thru WiFi that you must configure. Do neither of these work, or is it just the cellular connection that you have lost? If not connected to WiFi, you should see the LTE symbol and the signal strength in the upper right portion of the main screen. If you see the symbol with a slash across it, it means there is no cellular signal in the immediate area. If you see one or more bars lit in the signal strength, you are receiving the cellular signal. If you see no WiFi or LTE signal strength icon, you have a problem with your telematics in the car. You might want to try a power off reset using the button on the main screen to power off.
