Hanoi is 2 hours ahead of Islamabad
Best overlap: 8:00 AM to 4:00 PM in Islamabad is 10:00 AM to 6:00 PM in Hanoi.
Schedule calls for 8:00 AM to 4:00 PM in Islamabad — your colleagues in Hanoi will be online from 10:00 AM to 6:00 PM. Because you share 8 hours of the workday, there's no need to compromise; book the time that suits the meeting, not the map.