DNS Server - Synology Knowledge Center
kb.synology.com › en-global › DSMIf the DiskStation connects to the Internet through a router, set up port forwarding rules and open TCP and UDP port 53. Register your device: After you set up DNS Server, remember to register the IP address and other required information of your DiskStation with the provider of your domain name. Otherwise, clients will be unable to query your DiskStation over the Internet.