1. You need to set up Trickbyte dns on your router. Chromecast alone doesn’t have this feature. Click link below for how to set up
https://help.trickbyte.com/category/routers/
2. Google chromecast also has embedded Google dns. No matter what dns you set on your router, it will be always override by google dns. So you need to block them. Please visit link below for more info.
https://help.trickbyte.com/category/block-public-dns/
3. If you are going to buy google chromecast. Make sure your router has features above.
Note: You need to authorize your ip every time your ip has changed. To authorize your ip, sign in once to client area at http://www.trickbyte.com/signin then click “update ip” at the top.