1. In case the route starts or ends near the intersection, the routing sometimes treats the close segment as a start/endpoint.
To avoid such a problem we usually recommend not to set start/endpoints straight at the intersection.
The example is shown on the screenshot below, where the start point was set as point 1, but the system has chosen the point 2.

In case you use API, it would be always better to check if the route would be created in the portal to ensure there are no issues.
2. When the road is impassable the status of the created route would be Failed.
The same error could appear when the road network has changed.

3. We guarantee the availability of data for roads with the road classes from 0 to 4. In the case of the roads with lower FRC (5-7) – the data could still be available, but not for all of the segments.
4. In case the routing doesn’t create the route the way you expected, you can add the via points, so the route will cover all the roads you want.