If you’re Google Chromecast won’t connect to the wifi network during the setup process, here’s what to do.
If Chromecast is detected in the setup but won’t connect to the wifi network, then the issue is between the Chromecast and the wifi router. To fix this, try the following:
Connect to 5Ghz instead of 2.4Ghz, or vice versa
Update the firmware of your router
Try connecting as a guest to your wifi network if it’s supported
Try disabling the 5Ghz band and connecting Chromecast to the 2.4Ghz connection, or vice versa
Remove your Chromecast from the TV and try again
Plug Chromecast into a power socket
Make sure your Chromecast is within range of your wifi connection – maybe the signal is just weak where it currently is?
Buy a new wifi router
If Chromecast won’t connect to the wifi network and during setup you get no Chromecast detected, then the issue is related to the connection between your computer and Chromecast. Try the following:
Try rebooting your computer
Try connecting via a 5Ghz connection instead of 2.4Ghz, or vice versa
Try moving your computer closer to your Chromecast
Try running setup from another computer
If you find that you still have issues connecting Chromecast to your wifi network during setup, make sure that client isolation mode is disabled on your router, try playing with the wifi settings on your router (channel bandwidth, wifi encryption type, etc), try resetting your router to factory settings.
Also, note that the above tips assume that you are using a second generation Google Chromecast (the round one, not the USB stick style one), as the original Chromecast didn’t support 5Ghz networks.