1. Make clear the access address and port of the FTP service intranet, and ensure that the FTP service is normal and the intranet can access the connection normally.

2. Intranet uses nat 123 for dynamic domain name resolution. Intranet server installs nat 123 client and uses it.

3. Enter the main panel/domain name resolution list/add domain name.

4. Choose dynamic domain name resolution record, use free secondary domain name, or own domain name. The mouse is placed in the input box with the wizard prompt.

5. After adding dynamic resolution, check the current resolution status in the domain name resolution list. Dynamically resolve the domain name and keep corresponding to the local public network IP.

6. Open the FTP service access port in the intranet. Router port mapping location: forwarding rule /DMZ host/Enable DMZ and add FTP server that allows external network to access internal network.

7. When accessing external networks, use dynamic domain name resolution. When accessing an FTP service in an external network, the domain name is dynamically resolved for connection access. The domain name remains unchanged and can be accessed online, without worrying about the IP change of the dynamic public network.