GQ 231 then GQ 348 at Athens
Mykonos → Athens → Santorini
Timetable, Athens time
19:05GQ 231 from Mykonos at the gate
13:30GQ 348 to Santorini leaves the gate
18 h 25 apart on the timetable, overnight
GQ 348 leaves 18 h 25 after GQ 231 arrives on the timetable: more than half a day, so not a connection we count.