Unable to cast to Chromecast? You're not alone
A widespread outage is affecting older Chromecasts

An unwanted outage from Google's end is preventing Google Chromecast (2nd gen) and Chromecast Audio users from casting any content to their TV. They are also unable to access the device from the Google Home app. The outage appears to be due to a server-side disruption, with even common troubleshooting steps like restarting or rebooting the dongle not resolving the issue.