Portland is 14 hours behind Dhaka
There is no standard 8-to-6 overlap. Someone joins early or late.
The 14-hour offset between Dhaka and Portland means there's no point hunting for a 9-to-5 overlap — there isn't one. Expect compromise: someone in Dhaka or Portland will need to take the call outside the usual 9-to-5, so share that load. Keep an eye on the calendar — Portland observes daylight saving and Dhaka doesn't, which nudges this window by an hour twice a year.