GQ 671 then GQ 348 at Athens
Istanbul → Athens → Santorini
Timetable, Athens time
23:10GQ 671 from Istanbul at the gate
13:30GQ 348 to Santorini leaves the gate
14 h 20 apart on the timetable, overnight
GQ 348 leaves 14 h 20 after GQ 671 arrives on the timetable: more than half a day, so not a connection we count.