Hi @Robin_Wyatt1,
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 change in behavior if you uninstall Roon, reboot the phone and reinstall the Roon app from the iOS app store?