W4 6315 then LA 5746 at Barcelona
Milan → Barcelona → Firenze
Timetable, Barcelona time
12:25W4 6315 from Milan at the gate
10:45LA 5746 to Firenze leaves the gate
22 h 20 apart on the timetable, overnight
LA 5746 leaves 22 h 20 after W4 6315 arrives on the timetable: more than half a day, so not a connection we count.