– Chromecast is powered on and plugged into a wall outlet
– the LED light on the side of the Chromecast device is white
– you’re using the correct password
– in case you’re setting up from an iOS or Android device, you’re using the most recent version of the Google Home app. You can update it by selecting the following links:
— Android
— iOS
– your Chromecast is within 15 – 20 feet of the smartphone or tablet
If none of these tips work, maybe the issue is caused by your Internet connection:
— were there any recent changes to your network?
— did your ISP (Internet Service Provider) upgrade or make any changes to your router/modem?
Troubleshoot connection issues via Google Support
You could also use Google’s self-help flow to solve connection problems by visiting this page right here.
Troubleshoot general issues
1) Reboot the following devices:
– Wi-Fi router:
— unplug the power source for about 1 minute, then plug it back in
— if you’re unable to set up using the Netgear Nighthawk router, then you may need to 1) disable Access Control or 2) enable the option “Allow guests to see each other and access my local network” in the “Guest Network Setup”
– Chromecast device:
— disconnect the power cable from your Chromecast
— then reconnect the cable
2) Turn Wi-Fi off and on from the mobile device you’re using to set up Chromecast
3) If you have a dual band router, try setting up Chromecast on either the 2.4GHz or 5GHz bands
4) Perform a factory reset from your Chromecast device:
Chromecast 2nd gen, Ultra and with Google TV
– while the Chromecast is plugged into the TV and powered, press then hold the button on the back for a few seconds. The LED should start to blink yellow
– when the LED light turns completely white, release the button, and the Chromecast should then reset
Chromecast 1st gen
– while the Chromecast is plugged into the TV, hold down its button for at least 25 seconds, or until the LED light flashes red
– once the LED light blinks white and the TV goes blank, release the button. The device should then restart
Source: Chromecast Help