W6 423 then U2 1684 at Fiumicino
Krakow → Rome → Nice
Timetable, Rome time
20:28W6 423 from Krakow at the gate
19:45U2 1684 to Nice leaves the gate
23 h 17 apart on the timetable, overnight
U2 1684 leaves 23 h 17 after W6 423 arrives on the timetable: more than half a day, so not a connection we count.