Hi @poubelle_83,
the reason that you can’t get a route in openrouteservice is that the path from Chemin de Navette to your end point is tagged as having a sac scale as demanding_alpine_hiking (sac scale 5). Currently, the highest sac_scale we go up to is alpine_hiking (sac scale 4) as after that the paths can get very demanding and we don’t want to send people unwittingly along a route that needs specialist equipment and training and can be particularly dangerous for those that are not prepared.
We are looking at implementing something in the future where it could be possible to include the more demanding sac scales and then allow users to deselect them at routing time, but currently this is not possible.