UA 858 then TP 4392 at San Francisco
Shanghai → San Francisco → Boston
Timetable, San Francisco time
08:25UA 858 from Shanghai at the gatealso CA 7209
22:10TP 4392 to Boston leaves the gate
13 h 45 apart on the timetable
TP 4392 leaves 13 h 45 after UA 858 arrives on the timetable: more than half a day, so not a connection we count.