SN 3703 then FR 4545 at Barcelona
Brussels → Barcelona → Porto
Timetable, Barcelona time
16:50SN 3703 from Brussels at the gate
09:20FR 4545 to Porto leaves the gate
16 h 30 apart on the timetable, overnight
FR 4545 leaves 16 h 30 after SN 3703 arrives on the timetable: more than half a day, so not a connection we count.