If you're using www.openstreetmap.org to do navigation, after you rightclick and select "directions from here" you'll see a sidebar with three fields, the third field is the router.

I'm mentioning this because if you're downloading the map to OSMAND, using mkgmap to download to a Garmin, or other method, that is outside the scope of the map and you might be out of luck here as it could be a software issue versus a data issue.
