You should open the "C:\Program Files\Storj\Storage Node\config.yaml" with Notepad++ and replace the IP:28967 to your-ddns.hostname.org:28967 in the contact.external-address: option.
Save the config and restart the service either with a Services applet or from the elevated PowerShell:
Restart-Service storagenode
The your-ddns.hostname.org you can take from the Edit Hosts button
if your router supports the no-ip, it would be better to use your router instead of DUC. In this case the DUC will not be needed.