FR 4596 then SN 3704 at Barcelona
Porto → Barcelona → Brussels
Timetable, Barcelona time
00:50FR 4596 from Porto at the gate
17:40SN 3704 to Brussels leaves the gate
16 h 50 apart on the timetable
SN 3704 leaves 16 h 50 after FR 4596 arrives on the timetable: more than half a day, so not a connection we count.