QR 3617 then QR 4704 at Barcelona
Nantes → Barcelona → Porto
Timetable, Barcelona time
13:55QR 3617 from Nantes at the gatealso IB 5481, LL 5481, VY 8141
08:35QR 4704 to Porto leaves the gate
18 h 40 apart on the timetable, overnight
QR 4704 leaves 18 h 40 after QR 3617 arrives on the timetable: more than half a day, so not a connection we count.