DL 609 then DL 2597 at Atlanta
Cancún → Atlanta → Montréal
Timetable, Atlanta time
10:55DL 609 from Cancún at the gate
09:00DL 2597 to Montréal leaves the gate
22 h 05 apart on the timetable, overnight
DL 2597 leaves 22 h 05 after DL 609 arrives on the timetable: more than half a day, so not a connection we count.