To install this way, you must be sure your device that you can to change the Server address.
The default server address usually has the following format:
Please delete the above address and replace it with dyn.fastddns.net
If you can't change the updated Server address, Try installing it in a different way. here
Some common DDNS installation samples
The information after installation will be similar to the figure below
After installing DDNS information on the device, go back to the hostname information management page, wait from 30 seconds to 5 minutes to check if the ip address has been updated or not.
If you still don't see the updated IP address.