Lost iPad doesn't connect to WiFi
You can always restore an iPad that’s locked if you have possession of the device and the iCloud account. Also, connecting it over USB to iTunes will often allow you to get it unlocked promptly and on High Sierra - the Mac can share it’s network connection to iOS devices over USB so you don’t even need WiFi on the iPad for it to connect back to the internet and receive an update from iCloud/Apple for the unlock commands that are pending delivery.