UA 858 then UA 406 at San Francisco
Shanghai → San Francisco → Las Vegas
Timetable, San Francisco time
08:25UA 858 from Shanghai at the gatealso CA 7209
21:10UA 406 to Las Vegas leaves the gatealso AC 4025, VA 8562, LH 8940, NZ 9229
12 h 45 apart on the timetable
UA 406 leaves 12 h 45 after UA 858 arrives on the timetable: more than half a day, so not a connection we count.