Hi,
I don't understand German, but since the subject is about the same issue I ran into recently...I'm not sure if you even asked about this, since I used google translate. Anyway, you can use geomap_border to define the scale. For example, if you have all your hosts in same town, I used geomap_border value of about 0.001. I'm not sure what's the unit there (kilometers?). Anyway, the map zooms in properly once the geomap_border is small enough.