SL 394 then NH 803 at Narita
Bangkok Don Mueang → Tokyo → Singapore
Timetable, Tokyo time
17:15SL 394 from Bangkok Don Mueang at the gate
17:00NH 803 to Singapore leaves the gate
23 h 45 apart on the timetable, overnight
NH 803 leaves 23 h 45 after SL 394 arrives on the timetable: more than half a day, so not a connection we count.