Due to hardware and firmware limitations users with Gen 1 Chromecast devices will experience poor casting performance. We recommend using a Gen 2 or newer Chromecast devices for the best casting experience. Generation 1 is not receiving updates, which will lead to inability to cast.

Here is how you can determine your Chromecast generation https://www.howtogeek.com/438642/how-to-check-if-your-chromecast-is-still-getting-updates/