AS 535 then WN 988 at Denver
Seattle → Denver → Buffalo
Timetable, Denver time
13:58AS 535 from Seattle at the gate
11:50WN 988 to Buffalo leaves the gate
21 h 52 apart on the timetable, overnight
WN 988 leaves 21 h 52 after AS 535 arrives on the timetable: more than half a day, so not a connection we count.