Eurail passes work offline fortunately so you don't have to rely on poor network connection in some areas. Do not hesitate to put the phone in airplane mode, it works better.

You only need to connect to wifi/network every 72 hours or so + to activate the pass. Now I'm not sure if you need connection to activate a travel day.

All that to say : Eurail won't impact your data usage.

Thank you @thibcabe 

When you say to connect to wifi/network every 72 hours or so, I don’t have to do any hands-on action but just ensure data or wifi is there, right? 

Yes, you need to be online to activate a travel day. 

The best thing is to use the local train or public transport apps, for real time data and information. So I’lld add a bit more data to download an app here and there. 3 Gb maybe?

Make sure to check something like CityMapper, for local transport in the biggest cities.

@BrendanDB  For railway trains in France, the app would be SNCF Connect, right?

I have downloaded CityMapper already. Thanks. 
 

I also have Omio, but not sure what that is good for. Anyone can explain?

And also to generate the QR code, which is done by tapping on "Show ticket” for the first time after activating a travel day.

Indeed, SNCF connect. Although it’s not the best of apps. Sometimes it’s better to look here for rail time information https://www.sncf.com/en/booking-itinerary/itinerary (you can search easily on train number, which is impossible on sncf connect - very annoying).

Omio is not worth much, only theoretical train times, only updated every now and then.

Best install DB naviagtor, as it encompasses updated timetable information for almost all Europe (only real time for Germany and German trains abroad) or the respective national apps.

Thank you @AnnaB & @rvdborgt 

Thank you @BrendanDB 

• SNCF Connect: I find it awkward to use as it only provides a certain amount train schedule, there’s no “earlier” or “later” options as in 3rd parties such as Trainline or Rai Europe
• I will bookmark the link https://www.sncf.com/en/booking-itinerary/itinerary
• Deutsche Bahn: I already have and use quite often. I forgot to mention in my previous reply. Learned from Seat61 long ago about DB.
• Will delete Omio app

You’re welcome!

 Totally agreed. Very few options to customize your trip too, via options to e.g. taking a slower but more scenic line, add some extra exchange time,... SNCF Connect always has a tendency to steer you always towards the most expensive options. And sometimes it calculates double the price, than buying tickets via e.g. Deutsche Bahn. But that’s less of an issue here with your interrail, luckily.

Nothing to do but to give the SNCF app a bad rating ;)

@BrendanDB Glad to hear that it’s not just me being a rookie finding the SNCF Connect app so not user friendly. 

I’m in Canada so can’t use Deutsche Bahn to make a purchase, only to look at timetables.

That’s why I have an Eurail Pass instead of Interrrail pass. 

Of course you can use DB website or app to purchase tickets or seat reservations, even from Canada! Why wouldn’t it work?

(But if you already have Eurail, purchasing tickets won’t be useful. On the other hand seat reservations could be but I don’t think you’re visiting Germany at any point)

@thibcabe Ah I’m learning!! I always thought to use DB website/app to check timetable. So if I was visiting Germany for my trip with a Eurail pass, then it’s possible for me to make my seat reservation for the train trips in German on DB. Got it! Thanks a million.