UA 6213 then UA 3754 at Houston
St Louis → Houston → Waco
Timetable, Houston time
13:24UA 6213 from St Louis at the gate
11:30UA 3754 to Waco leaves the gate
22 h 06 apart on the timetable, overnight
UA 3754 leaves 22 h 06 after UA 6213 arrives on the timetable: more than half a day, so not a connection we count.