If you are having trouble connecting your Chromecast and you are not connecting to it then make sure you are using the correct login details. If you have lost the password, try resetting it.
If you’re using an iOS or Android device to set it up, make sure you’re using the most recent version of the Google Home app. The Chromecast gadget should be placed 15 to 20 feet away from the mobile device or tablet you’ll use to set it up.