Hello @Philip_Martin — Thank you for sharing your report with us, it’s appreciated!
To start, may I kindly ask that 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.
Since experiencing this behavior have you tried rebooting your Core machine, the Synology, remote device, and any applicable networking hardware?
-Dylan