UA 1783 then B6 177 at Boston
Los Angeles → Boston → Las Vegas
Timetable, Boston time
17:38UA 1783 from Los Angeles at the gate
17:20B6 177 to Las Vegas leaves the gate
23 h 42 apart on the timetable, overnight
B6 177 leaves 23 h 42 after UA 1783 arrives on the timetable: more than half a day, so not a connection we count.