UA 571 then B6 1734 at San Francisco
Atlanta → San Francisco → Boston
Timetable, San Francisco time
11:24UA 571 from Atlanta at the gatealso VA 8403, NZ 9005
10:44B6 1734 to Boston leaves the gatealso FI 7830
23 h 20 apart on the timetable, overnight
B6 1734 leaves 23 h 20 after UA 571 arrives on the timetable: more than half a day, so not a connection we count.