Ni->Gi can do easily on local/regional trains without even chance to RES. Chnage in border station Port Bou from FR-TER to broad gauge ES rodalies (Express Catalan). Is even better: stops in central Gir, whereas hi-speed in a station 6-7 Kms away.

IFwanting to save money-and have much more choice in trips; also use local trains from St till Strasbourg and in TGV from there (INland rules then).

This forum brims with very anxious people who all seem to think that trains are sold out monthes advance, which is complete nonsense. You did not clearly state via what way you want to RES, but I guess its that app which is labelled here all the time with many faults. This is probably also 1 of them.

IF you are new here, anna B fra Sverige will also post a long list of tips, incl an overveiw on how to RES by yourself for less too by seewulf.

Thanks mcadv! Yes, I am a newbie and I’m anxious, and these are good suggestions to calm me down. It doesn’t solve the puzzle, though, that I’ve asked about. Why can’t I reserve seats more than 90 days in advance, but can buy tickets for the same trains with a seat reservation (way more than 90 days in advance)?

By the way, I have discovered that I can reserve tickets directly, not with the Eurail app reservation system, which has two advantages: 1. (more importantly) that seats are still available when the reservation app says that they have sold out, 2. it is cheaper. I’ve found Venice-Vienna seats this way for 3 euros only on ÖBB (the app says 12 euros and no longer available).  

On a different note, since you are so knowledgeable, can you suggest a route without mandatory reservations from Nice to Venice (Venezia)? 

If it's possible to do a reservation for a train right now in general, it should be also possible when holding a rail pass. And in most cases there should be no difference in availabilty. But it depends on train and route. And a general "90 days in advance" isn't correct - it depends. So if you did find a train that is already available there is a big chance you are able to do a reservation with your railpass, too.

Regarding your Venice to Vienna reservation: Unfortunately, you didn't find a cheap way to get your reservation, you just found a wrong way. I hope you didn"t buy one yet. For the direct trains, you'd need a supplement as a railpass holder that includes a reservation. That's 10 € when bought with ÖBB (that's possible but not that way you obviously used) - interrail / eurail charges an additional 2 € reservation fee - that's why it is 12 € there. But if you bought a reservation for 3 €, you'd still need a supplement for 10 € which would include the reservation, so you'd pay 13 € all together.

Regarding availabllity: There are countries/ trains where there is just a quota of places for railpass holders, for instance with Eurostar to and from London. So you may get places when you'd buy a normal ticket but not as a railpass holder. So the app may also be right that the seats for railpass holders are sold out. That has not to mean that the train is sold out. But there are also countries/trains where there is no such difference. 

Going from Nice to Venice without a reservation is possible but it means more changes (Ventimiglia - Genova - Milano - Verona) and is slighlty longer (to get you an idea: when leaving Nice Ville at 8.50, you'd arrive Venice Santa Lucia at 19.50). 

Hi Hektor, thanks for your responses. I understand the logic that if I can buy a ticket for a train with reservations, then I should be able to get just a seat reservation at the same time. This is precisely why I am puzzled by the discrepancy that I’ve found. Here is a specific example: Nimes-Girona, June 14. The Eurail reservation system says trains can be booked up to 90 days in advance, but I can already buy a ticket on SNCF Connect. I’ve checked elsewhere too and couldn’t pin down when the reservations would open, although most sources say 90 days. Are you saying that the Eurail reservation system cannot be trusted? If so, where would I be able to get this reservation instead? SNCF Connect does not seem to have an option to get a reservation only.

Also, I didn’t say that 90 days is the general rule. I have seen 90 and 120 days so far for different trains and routes, and clearly the Venice-Vienna train sales are open for even longer, as the seat reservation that I got for 3 euros is for June 22nd. I’ve found 90 days indicated for the specific routes I mentioned, and I didn’t refer to other time periods and routes so as not to complicate things.

As for the supplement for the Venice-Vienna train, I don’t doubt that you are right, but how is one to figure this out and how is one to pay it, even more importantly? The app says seats are sold out, there is no mention of any supplement there, and ÖBB let me buy the 3-euro seat reservation. So what now? When and how do I pay this supplement?

Finally, thanks for the Nice-Venice tips. So far there are no trains indicated for my dates, and the time frame is not clear, as usual. The cutoff for finding any trains going towards Italy from Nice (without a huge detour) seems to be 137 days… how does this make sense? 

Reservations for trains within France can be bought here: https://travel.b-europe.com/Eurail-GE/en/booking-tgv#TravelWish

But directly to Spain is not possible here (direct trains are expensive for railpass holder, too). But if you are willing to change trains at Port Bou, it's also possible to go without a reservation. Same disadvantages as with Nice to Venezia (less comfortable regional train, more changes, slower).

If you don't want to wait, you may book with SNCF by phone (press #85 for english). But it doesn't always work. And you're right, it's not possible to do the reservation online with SNCF.

For Venice to Vienna: You may know this because the app teils you that you'd need a reservation for 10 € + 2 € = 12 (with eurail, you'll always have 2 € reservation fee).

When booking with ÖBB, you may not choose "reservation only", you have to choose "one way-tickets and day tickets' and then choose "Interrail / Eurail - Globalpass" as a discount (you'll need to tap "change" where there is written "1 x adult" and then "add discount" on the next screen). Then it will show the correct supplement/ reservation. 

You didn't tell the system that you do hold a railpass so the system can't know this and gave you the wrong reservation (just for holder of normal tickets). You are not allowed to go with your 3 € reservation, you'll need the supplement. Book it the way described before.

For Europe, there's a timetable change the 2nd weekend in June. Some railways provide data for the whole year, Trenitalia doesn't. Plan with todays timetable to get an idea what connections are possible. Expect it to be May for regional trains (but you don't need to reserve them anyway).

Thanks, Hektor! I have now bought the reservation correctly for the Venice-Vienna train. Now I’d wished that there was such an online reservation system for France-Spain. But I guess I’ll just take more trains and go slowly to and from Girona. And, I’ll buy a cheap bus ticket from Nice to Venice. It saves one day on my Eurail pass and it’s a direct bus, so I won’t need to change 3-4 times - yay! 

Thank you again, I appreciate your help.