Portland is 11 hours behind Riyadh
There is no standard 8-to-6 overlap. Someone joins early or late.
Set against an 11-hour difference, Riyadh and Portland run their workdays on completely separate schedules. Block a single recurring off-hours slot that both teams agree on, rather than negotiating a new awkward time every week. Note that Portland follows daylight saving while Riyadh stays put, so the times above drift by an hour seasonally.