Supplement 20.12.2012
-------------------
The power supply was broken after less than 9 months and could easily lead to the apartment fire, since the power supply is not simply "did not work", but was extremely hot.
In addition, there was also a limitation in the use (which I always thought that it was up to my computer, or firewall settings).
I use the software OpenVPN to open a VPN tunnel. Normally: Open program, connect ready. With the above I had to switch my machine but always necessarily give a fixed IP, so the VPN tunnel status. But I forgave a fixed IP, I could not turn over the Fritz box to the Internet or to the NAS. So fixed IP to the VPN tunnel and DHCP to connect to the Internet or to connect to the NAS.
The switch was broken, I bought D-Link DES-1005D Fast Ethernet 5-port switch, since it does not matter if I have a static IP or DHCP, both the VPN tunnel, as well as the Internet and the NAS function.