I spent an entire night for a solution to the 'cannot communicate with Chromecast' issue after we changed our WiFi,
I could not cast from my devices to my smart TV which had been working just fine before the change.
There were no solutions online for resetting Chromecast without a 'Device Tile' as Google calls it (I would say it was a 'Room Tile'). There was no tile for me to 'hold down' to reset to factory settings or remove the old network. The room had been deleted and Chromecast kept trying to connect to the old network. I tried everything I read on the internet, rebooting, uninstalling etc.
I finally went to bed and, when I got up, had an idea which I tried and it worked! It may not work for you but sharing as, if it does, it will end long phone calls etc.
Here's how I did it:
1. I uninstalled the Home app on my android device
2. I reset the Chromecast dongle by holding down the button on the side while it flashed orange and then went to a steady white, after which I let go
3. I removed the Chromecast dongle from the TV (removed it from the HDMI port) but left it plugged in to the power so it was still on the network
4. I reinstalled the Home app on my android device
5. I clicked 'Set-up Chromecast' in the app and followed the instructions to set up a room
6. When the app asked me if I had a certain code (it's a four digit code with letters and numbers) I answered 'Yes'
7. The instructions asked for my network and I chose the new one and entered the new password
8. I completed all the instructions and it gave me a new 'Room Tile'
9. Finally I plugged the Chromecast back into the HDMI port after which, I was able to cast using all my devices
I hope this helps you.
