Thanks for reaching out to the Chromecast Community forum.
olinna, based on the screenshot of the Google Home app that you've shared, it looks like you're asked to disable the AP isolation in your router settings. If the AP isolation setting is enabled in your router, it will prevent your phone/tablet/laptop computer from communicating with the Chromecast device. If you're not familiar with how to configure this, please reach out to your router manufacturer or ISP for further help.
Jo1313, could you tell us what specific Nest product you have? Also, please provide as many details as you can to describe your issue so we can further assist you.