Thanks for letting us know. Kurviger uses data from OpenStreetMap (OSM). The data in OSM is entered and maintained by volunteers. Therefore, the quality of the data varies between different countries. You could go ahead and add the missing road to OSM, with the next update in Kurviger, we will be able to calculate a route to this position.
Hm Kurviger actually already drives up until that “dip” in the road here, but then stops. In the OSM data I don’t see a gate or a change in surface or admission rights. Did somebody here already change the OSM?
BTW: You can show the history for any object in OSM by opening the object, scrolling down on the left side and click on “View History” on the bottom of the panel.