Portland is 9 hours behind Stockholm
Best overlap: 5:00 PM to 6:00 PM in Stockholm is 8:00 AM to 9:00 AM in Portland.
The overlap falls at 5:00 PM to 6:00 PM in Stockholm, or 8:00 AM to 9:00 AM if you're in Portland. Because Portland is 9 hours behind Stockholm, the shared window is only about 1 hour. A fixed slot at 5:00 PM in Stockholm (8:00 AM in Portland) saves a lot of back-and-forth.