Ok, it's not that impressive but this route is in my backyard and unclaimed, so I went for the lowest hanging fruit.
The starting point is right next to the last stop of the bus line 300 which has multiple stops in Hannover. From the end point of the route it's less then 2,5km to the Nordstemmen train station from which you can return to Hannover within a couple of minutes.
The route is marked but only sparsely. 20 minutes in my Garmin finally got it's shit together and from then on it was pretty easy to navigate.
At around 15km the main path goes left but you take a right turn. The trail sits very low between two lakes and due to the rain in the days prior there was a roughly 40 meter section of trail flooded almost knee deep with freezing water.