Hey @wwwizzarrdry,
I moved your post to it’s own thread so we can take a closer look at what you’re experiencing here.
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.
Can you share a screenshot of how you have things grouped in Roon, as well as the signal path when playing to this zone?
Are you able to play to each zone individually without issue?
Thanks,
Dylan