Bahn.de recognises Brussels in at least 4 languages (and is a good timetable source) but you can't book this TGV there. You can book it online via Eurail or by phone via a number of operators.

The TER Lyon-Geneva does not have reservations. Just board and find a seat.

Thank you @rvdborgt for your detailed response.

Hi @rvdborgt ,

Eurail.com does not allow me to make this booking. Below is the error message.

 

What are my options to make this seat reservation?

Thanks

We don’t know why but for a few weeks it has not been possible to book a Belgium - France TGV on eurail.com or interrail.eu

Either you wait a few days until the problem is resolved (hopefully !) or you can call SNCF here :

https://www.sncf.com/en/customer-service/contact-us/telephone (press #85 for English, no booking fee, delivery via e-mail).

Hi @thibcabe ,

Thank you for your clarification.
Is there a way to know how much would this seat reservation cost (besides calling SNCF)?

https://www.eurail.com/en/plan-your-trip/about-reservations/reservation-fees

€20 in 2nd and €30 in 1st class.

It looks like this train does not have pass holder seats left in 2nd class, only in 1st. But then you need a 1st class pass.

Is there a quota for the Belgium - France TGVs ? Because there are still dozens of 2nd class seats left at 78€ (regular ticket).

SNCF should be able to tell you

Yes there is and it sells out very fast. Typically, when there are no pass holder seats left from Brussels, you will still find €10 pass holder seats from Lille.

This is the second post I have seen about shortage of seats in France that weekend. Apparently it is because it is Ascension Weekend and France has “le Weekend”.

I don’t think that’s the case here. Ascension weekend happens between 18 and 21.05. It is a holiday in France, Belgium, the Netherlands, Switzerland, Germany as far as I know.

But 25th June is going towards the summer holidays...

O yes, that weekend will be very busy. Expect e.g. TGVs from Marseille to Paris on Sunday 21 May to be fully book weeks in advance. They're already almost fully booked, see www.sncf-connect.com. Only some places left at 6:13 and in the evening.