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.
Have you made sure that you are using the latest Roon build for both your Core and Remotes? You can check this under
Roon Settings -> About and I would make sure it says build 571 for both.