Raspberry Pi in Simulink IP and SSH issue

Okay, I hope I can explain my problem properly. I installed the ML and SL support packages for Raspi. The first time i wrote an image to the Raspi using Matlab i chose 'Direct connection to host computer'. In this case Matlab's installation process writes a static IP to the Raspi and the test connection and also some test models in Simulink worked fine. The problem is that I also need internet access, but I cant share my host computer's internet connection with the raspi. My company patched a DSL port under my desk for me, so I can reach the internet. In terms of this. I edited /etc/network/interfaces for dhcp usage. From this DSL port the Raspi gets a Gateway, Netmask and IP (always the same values). My host computer is hanging via Ethernet in the company's internal network, which has a big firewall between it and the internet. The Raspi hanging on the DSL port and the host computer don't have any network connection to each other. What do I have to do in order to use the DSL Port to get internet access, but also reach the raspi from ML/SL from my host computer? I just cannot figure it out. Even if I give the pi a static IP and change it accordingly in the Run-to-Hardware-Options, I get "Error connecting to SSH server at IP" I also tried to write the image on the sd card again with the "Automatically get IP address" and "manually enter IP address" (latter to enter the gateway, mask and ip that i get from the dsl port), but the test connection always fails with the ssh error :( I want the following: For internet access connect the raspi and the DSL port. Then, to deploy a simulink model onto the pi, change the cable, connect the raspi directly with the host computer and reach the raspi with the same gateway, netmask and ip that it received beforehand from the dsl port.

Any help is greatly appreciated, Thanks