There are a few things you can check and try for this kind of issue;
- Make sure your Chromecast is within 15 - 20 ft (4 - 6 m) of the Wi-Fi router. If you have a dual band router, try to set up your device on both the 2.4 GHz and 5 GHz bands.
- Make sure Wi-Fi and Bluetooth are both turned ON on your phone or tablet.
- Turn OFF mobile/cellular data.
- Reboot your router. Most routers just require that you unplug the power source and then plug it back in to reboot.
- Reboot Chromecast by removing the power cable, then reconnect it.
- Make sure you're using the latest version of the Google Home app, by checking your app store for any updates.
- Restart the Google Home app.
- Android: Swipe up from the bottom, hold, then let go. Swipe up on the Google Home app.
- iPhone/iPad: Swipe up from the bottom, hold, then let go. Swipe up on the Google Home app. On older devices with a home button, double-click the Home button, then swipe up on the Google Home app.
- Turn Wi-Fi off and on again on your phone or tablet.
- Reopen the Google Home app.
If none of the steps above help, factory reset your Chromecast and then retry setup. You may also want to try setup using a different phone or tablet, just to test, if you have one.
