Public IP for Sharing Files

Hello everybody,

I am a new user of Owncloud.
Owncloud runs on a Linux client with the IP 192.168.1.150. In addition, I have a fixed IP from my provider with 8x.xxx.xxx.x.xxx. 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 (192.168.1.150). Can you change this so that only the external IP is used?

Thank you in advance for your help
Alexander