here is the reply of my regional d-link support.
Dear Customer,
The product uses the following ports for Web Server Services and mydlink 80 , 443 , 2047 , 2048 .
The port 80 can not be changed DSP side , please therefore to assign a different port management for the product DSR or other products that want to reach the outside.
So or i use the dsp and close the port 80 or i use the webserver and throw out the window two dsp (100 euros).
i think it is a crazy thing.