Addition: this is a BUS and train combo-till Kiato its bus-they wanted to rebuild the old meter gauge to new normal gauge, but the money ran out-or corruption maybe used it up. Tickets/passes also valid on THIS bus (NOT the direct KTEL buses-faster and more often and for longer hours) and NO RES needed nor even possible.
There are scores of ferries from IT to GR-via various ports and these ships never appear in planner apps of railways. The best and most used jump off from IT is in fact Brindisi. Google will provide details in millisecs-as it mostly does-first will come paid combined ferrybookers-use these as comparison, then find the site of the comp. you choose. NO free trips-most give discounts.
Hello, I appreciate that this information is likely too late to be useful, but just in case other travelers had the same question:
Greece does not share their timetable data with us, so you'll need to check the information directly on Hellenic Train's website. There is a train from Patras to Athens via Kiato that takes about 3 hours. You can simply add this journey manually in the app and purchase seat reservations locally at the station if needed.