Shanghai is 14 hours ahead of Denver

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

The 14-hour offset between Denver and Shanghai means there's no point hunting for a 9-to-5 overlap — there isn't one. Expect compromise: someone in Denver or Shanghai will need to take the call outside the usual 9-to-5, so share that load. Remember that Denver shifts for daylight saving and Shanghai doesn't, so recalculate the overlap after each clock change.