Ethernet, how to read the login page of a router

Using the browser I just enter (or whatever it may be) to get to the login page.
To access the start page you do not need to enter any file name.
The well-known Arduino Ethernet example shows the usage:

    // Make a HTTP request:
    client.println("GET /search?q=arduino HTTP/1.1");

Of course I know I have to replace the host name.
But whatever I insert between GET and HTTP (even * and ?) the Arduino does not get any bytes as response.
Any idea?

Try just "/", as in GET / HTTP/1.1.