Webinterface issues

Hello,

I have encountered a very odd behaviour regarding the webinterface. I have enabled all the settings like allow HTTP access etc, set a user and a password.
Portforwarding on my router as well as a static address for my device.

Everything works as expected, i can access my kodi box within my network and control everything via the webinterface.
Now if i access my kodi box from outside my network i get access to the webinterface but can´t control anything. So non of the commands are beeing recognized and i can´t get any information of the box like what is currently playing or the media library.

I am out of ideas and hope that someone here can help me with this issue.
Thank you in advance.