EC 3749 then IB 5092 at Barcelona
Milan → Barcelona → Porto
Timetable, Barcelona time
21:30EC 3749 from Milan at the gate
12:55IB 5092 to Porto leaves the gate
15 h 25 apart on the timetable, overnight
IB 5092 leaves 15 h 25 after EC 3749 arrives on the timetable: more than half a day, so not a connection we count.