The link was helpful, but didn't use the whole tip. I went to the network and sharing center. There was my network connection and on the right was a link something like "show the whole connection setup. And there I found a diagram of my whole network: Computer, wireless router, wired router. And I just clicked on the routers and came directly to the IP I was looking for. 192.168.1.4.
And then I could change my password.
Thanks a lot ...