UA 6211 then DL 2709 at Houston
Lubbock → Houston → Atlanta
Timetable, Houston time
11:03UA 6211 from Lubbock at the gate
08:05DL 2709 to Atlanta leaves the gate
21 h 02 apart on the timetable, overnight
DL 2709 leaves 21 h 02 after UA 6211 arrives on the timetable: more than half a day, so not a connection we count.