Public IP for Sharing Files

Hello everybody,

I am a new user of Owncloud.
Owncloud runs on a Linux client with the IP In addition, I have a fixed IP from my provider with I enabled this IP in the router and forwarded a port to Owncloud. So far so good. I can access Owncloud from outside my network.

However, when I want to share a file, OwnCloud always creates a URL with the internal IP ( Can you change this so that only the external IP is used?

Thank you in advance for your help