Santiago is 10 hours behind Hanoi

There is no standard 8-to-6 overlap. Someone joins early or late.

Santiago is 10 hours behind Hanoi, which is far enough that a normal 9-to-5 in one city never reaches the other's working hours. One practical option: Santiago dials in early while it's still late afternoon or evening in Hanoi. Finally, Santiago observes daylight saving and Hanoi doesn't, so this window shifts by an hour for part of the year — recheck it each spring and autumn.