UA 4301 then UA 6243 at Houston
Lubbock → Houston → St Louis
Timetable, Houston time
18:41UA 4301 from Lubbock at the gate
12:05UA 6243 to St Louis leaves the gate
17 h 24 apart on the timetable, overnight
UA 6243 leaves 17 h 24 after UA 4301 arrives on the timetable: more than half a day, so not a connection we count.