Hanoi is 11 hours ahead of Philadelphia

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

Hanoi is 11 hours ahead of Philadelphia, so their typical working days don't line up at all. Plan on one side joining outside normal hours. A recurring slot that trades off between early mornings and late evenings usually works best. Heads up: because Philadelphia changes its clocks and Hanoi doesn't, the difference moves by an hour twice a year. Confirm the overlap around the DST switch.