As you say, the question pronoun corresponding to

> Ich komme nicht auf das Netzwerklaufwerk

is ***wohin***, so it's rather a determination of the **direction** than of location. This makes the difference because the prepositions

> an, auf, hinter, in, neben, über, unter, vor, zwischen

are called [***Wechselpräposition***](https://learngerman.dw.com/de/wechselpr%C3%A4positionen-3/l-40581904/gr-40585492) and can [govern](https://en.wikipedia.org/wiki/Case_government) either the dative or the accusative, changing their meaning. When they describe a location (as in *auf dem Netzlaufwerk speichern – wo?*), they govern the dative. If they are used to indicate a location (*auf das Netzlaufwerk kommen – wohin?*), they go with the accusative.

As a native speaker, you will intuitively understand the difference between *Ich gehe auf dem Boot* (dative) and *Ich gehe auf das Boot* (accusative).* You might also have heard the verb *kommen* getting an insinuating meaning when used with a *Wechselpräposition* governing the dative (see no. 17 [here](https://www.duden.de/rechtschreibung/kommen#bedeutungen)): *Ich komme auf das Sofa* (accusative, direction, standard meaning) vs. *Ich komme auf dem Sofa* (dative, location, insinuating meaning).

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*This example is similar to tofro's, but better comparable to the original sentences because it's neuter as well and hence uses the same articles.