There is another way to download a route and not waste time downloading thousands of objects and then find that there are hundreds of unknown objects.
1- Select the route you want to download from the DLS in the Content Organizer.
2- Right-click on the selected route.
3- In the window that opens select: "Download this version".
4- It will start downloading only the route without the dependent objects.
5- It is necessary to be pending of the download, because when it finishes, it will begin to download the dependent objects.
6- Just when the download of the route is finished, you have to close the open window of the download called: " Downloading... ".
7- Search for the downloaded route in the Content Organizer, with the filter installed today.
8- Select the downloaded route and with the right button select: "List Dependencies".
9- See the dependencies of the route and if it has many unknown objects according to our scale, we will be able to eliminate the route or to unload the objects that we lack. In my personal scale if a route has more than 10 unknown objects I do not download the route or I eliminate it directly.