For a meaningful answer, please specify your travel date(s).

Booking via ÖBB should result in a PDF reservation. If the train is bookable via Interrail, then it should also be bookable directly via ÖBB. For which date was that?

Sorry! Dates are from 24th of july? 25, 23 is also an option.

Paper ticket option was for the same dates.. I don't see that option now btw..

Paper ticket option..

I'm able to book it through tickets.oebb.at : add Interrail as a discount and select one-way tickets. 24th July Zagreb - Ulm

158.10€ for a 3-people sleeper, directly sent by email.

However are you looking at the journey from Ulm to Zagreb ? Then there's less availability.

- 22nd-24th July : only seats left

- 25th July : seats and couchettes in a shared compartment available

Btw the 10-min connection in Ulm is not advised at all, night trains are often delayed. It's best to go all the way to Stuttgart and continue your onward journey from there, including a 45 min-1h break if possible.

Seat reservations are recommended on German ICE in summer :

- 4.90€ per journey through bahn.com

23 & 25 July: only couchettes and seats available. 24 July: also sleeper available:

Train continues until Stuttgart.

Book ASAP. Add the Interrail discount for all passengers, then choose "One-way tickets”, NOT "Seat reservation only”. If that doesn't work, then try via www.nightjet.com. There you only have to add the discount and you can't use the wrong search option.

Sorry, must be some confussion.

Train from the Netherlands - Zagreb 24 (25-23 july) 

The printscreen with the papier ticket was Zagreb - NL at 11-8

I think the option you saw is 11-8 from Germany - Zagreb.. unfortunately thats the end of our holiday :(

23 & 25 July: only couchettes and seats available. 24 July: also sleeper available:

Train continues until Stuttgart.

Book ASAP. Add the Interrail discount for all passengers, then choose "One-way tickets”, NOT "Seat reservation only”. If that doesn't work, then try via www.nightjet.com. There you only have to add the discount and you can't use the wrong search option.

The only options I see are without couchette/ sleepers? (same for the last couple of days..) both at öbb and nightjet

Yes there are only seats left unfortunately… night trains are very popular and do not have a lot of capacity. At least not enough for the demand

I’m looking at alternatives : what is your final destination ? There are night trains to Split but they don’t run daily and are also pretty booked.

• night train to Ancona and from there there’s an overnight ferry to Split : Deluxe sleepers available on 24th July or a 4-people couchette for 176€ (you book the whole compartment)
• updating…

The return journey will also be complicated. Is 11th August a set date ? Here are the alternatives :

I have no specific final destination. We wanted to go to Croatia and then (in advance) complete the journey there. I think we will now go from the Netherlands to Munich (or something like that..), sleep there for 1 night and from Munich to Zagreb. I had no idea Croatia would be so tricky! Last year to Switzerland/Italy everything went so smoothly. Anconda is an option, but then we are traveling for a long time..
Split also an option but not much available I see..

11th of august is not set, as long as we are in NL on sunday

An interesting way to go to Zagreb :)

• trains to Zurich from your hometown (do not use interrail.eu to make the seat reservations, way too expensive). The best route is via Germany
• 24th July 20:40 - 25th July 06:58 162€ for a 4-people couchette compartment (book 4 tickets) OR
• 25th July : 3-people sleeper for 149€
• spend a few hours in Graz, there are luggage lockers at the railway station
• EC Graz - Zagreb Glavni Kol 18:39 - 22:25

For the return there would be the expensive sleeper from Split direct to Vienna :

• 10th August 17:20 - 11th August 09:21 284.70€ for a 3-people sleeper…

Or the option via Graz :

• EC Zagreb Glavni Kol - Graz Hbf 07:05 - 11:22
• Nightjet  Graz Hbf - Zürich Hbf 22:25 - 09:20 all accommodation available

Btw Slovenia is also a good destination for a few days if you’d like.

Other options :

• daytime trains
• night train Munich - Ancona (and back) and then a ferry to Split
• night train to Venice + train to Ljubljana or Flixbus to Croatia (way faster than the train)

Almost all the nighttrains to Zurich (thus Italy from here), Vienna, Munich are booked. Seats are available but with kids who really need their sleep we prefer a bed. You mentioned ‘book 4 tickets’ 

When I select the seating carriage https://www.nightjet.com/en/komfortkategorien/ganzes-abteil-buchen, private is not avaliable.. Can I book for 6 to make it private? Do you know if it is def. that the 3 of us are seated in the same carriage? 

Which night trains are you looking at ? I tried to add night trains with availability :

• either in a 3-people sleeper
• or in a 4-people couchette compartment. You book 4 tickets so you have the full compartment to yourselves. It will be explicitely written if you’re not together. Tickets are fully refundable if there’s a problem suddenly.

I agree that couchettes/sleepers are way more comfortable.

If I make another summary with availability around 24th July :

• Zurich - Graz : 4-people compartment for 162.40€ (23, 24, 25) or 3-people sleeper for 149.40€ (25th July)
• Zurich - Vienna : 4-people compartment for 162.40€ (23, 25)
• Zurich - Budapest : 4-people compartment for 196€ (24, 25) or 3-people sleeper for 177€ (25) through tickets.oebb.at (not nightjet.com)
• Stuttgart - Budapest : 3-people sleeper for 177€ (23, 25)
• Stuttgart - Vienna : 3-people sleeper for 177€ (23, 25)
• Munich - Ancona : 3-people sleeper for 217.20€ (25)

Direct train between Budapest and Zagreb :)

Indeed most trains are full so you need to book ASAP whichever option you choose.

For the return journey :

• Split - Vienna : 284.70€ for a 3-people sleeper (10th August). Very expensive…
• Graz - Zurich : 3-people sleeper for 149.40€ (10)
• Ancona - Munich : 3-people sleeper for 217.20€ (10, 11)

I may have forgotten a few routes but I don’t think so. I’d choose the Zurich - Graz route (at least one way).