Google has apparently released an update to the firmware on the Chromecast. Perhaps after many reports of issues with a variety of routers.
This morning the update was downloaded and the updated applied automatically.
Now instead of the google.com(https://cast.google.com/chromecast/setup?np=thankyou) link you can go to
Set me up:
On your laptop or phone, visit chromecast.com/setup
The images look a little different.
Trying the new setup now to see if it works better than the previous firmware.
The update appears to fix several issues when attempting to setup the Chromecast in particular the issues with some routers.
The software on your Chrome browser although still beta appears to work fairly well. You must use the Google Chrome browser in order to work the Chromecast.
You can see the latest version of the firmware in the Chromecast app. Latest Chromcast firmware appears to be 14651.