I can’t connect my MacBook Air to our internet

First try and to restart your mac. If this is not working, Please try this Wi-Fi Recommendations. Click Wi-Fi  in Control Center or the menu bar and check for a menu item named Wi-Fi Recommendations. If you see it, your Mac has detected an issue and has recommendations. Choose Wi-Fi Recommendations to learn more.*

Wireless Diagnostics. Press and hold the Option key on your keyboard while clicking Wi-Fi  in Control Center or the menu bar, then choose Open Wireless Diagnostics from the menu. Learn more about using Wireless Diagnostics to analyze your wireless environment.

Are your other Devices working on the WiFi? Of not, you can try and update your WiFi router