You could try the maps from openfietsmap.nl or velomaps.org (especially the openmtbmaps maps).
In theory these should offer the ability to route down tracks or canal paths but routing can often be a bit trial-and-error as it depends on the settings on your device, and the way the map is set up - and occasionally, with OSM maps, you can find that two bits of a way aren't connected.
The fact that a map shows contour lines won't in itself affect how the device does routing. So it may be that the problem is with your device settings.