Hanoi is 1.5 hours ahead of Hyderabad
Best overlap: 8:30 AM to 4:30 PM in Hyderabad is 10:00 AM to 6:00 PM in Hanoi.
If you set up a recurring sync, 8:30 AM to 4:30 PM in Hyderabad (10:00 AM to 6:00 PM in Hanoi) is the natural home for it. Because you share 8 hours of the workday, there's no need to compromise; book the time that suits the meeting, not the map.