I planed the course on strava, showing 2671m total ascent. However, after the ride, edge 830 only gave me a 2147m total ascent, while the strave showed 2605m after correction.
I've rode a similar route before, with one more climbing around 100m ascent, resulting in 2537m total ascent by another head unit. So I suspect the actual total ascent this time should be around 2400m, which is underestimated by edge 830.
Strava route
Edge 830 result
Edge 830 altitude
After strava correction