Hi @Ian_Robson,
So we can better assist you, please provide a brief description of your current setup using this link as a guide.
Make sure to describe your network configuration/topology, including any networking hardware currently in use, so we can have a clear understanding of how your devices are communicating.
Is there any specific content that seems to cause this error to occur (streaming vs local, certain sample rates, etc.)?
Outside of Chromecast is everything working as expected with the same content?