Place "Check internet connection" element somewhere on the page and make sure it's visible. Check connection:
Use the state "Online" to check if the user is connected to the internet or not. If the state evaluates to "yes", user is connected to the internet, otherwise the user is not connected to the internet.

Check Speed:
Use the state "Speed" to check network speed of the user in Mbps.

Demo - https://internet-checker.bubbleapps.io/version-test?debug_mode=true