GQ 21 then A3 354 at Athens
Syros → Athens → Santorini
Timetable, Athens time
14:00GQ 21 from Syros at the gate
10:30A3 354 to Santorini leaves the gate
20 h 30 apart on the timetable, overnight
A3 354 leaves 20 h 30 after GQ 21 arrives on the timetable: more than half a day, so not a connection we count.