Hi, I think found a bug on the router engine, where if you put too many waypoints close to each other it will return a 207.
To reproduce, I have first created a route with only three waypoints, which resolves fine:

API Call:
http://router.project-osrm.org/viaroute?loc=52.363238,4.896394&loc=52.363860,4.901361&loc=52.362845,4.898432
Map of the waypoints used:
http://i.imgur.com/IZ3APL3.png

Using the same route, but adding more waypoints in between returns a 207 instead:

API Call:
http://router.project-osrm.org/viaroute?loc=52.363238,4.896394&loc=52.363480,4.897746&loc=52.363834,4.899548&loc=52.364024,4.901308&loc=52.363389,4.901351&loc=52.362845,4.898390

Map of the waypoints used:
http://i.imgur.com/jIDPjHm.png