Thanks a lot for your replies, looks like the community is still very reactive
So here is a quick summary of what I did : I was indeed able to display 4 (!) empty servers by checking the appropriate checkbox, but no player eventually came to join me on one of them
(I didn't wait more than 5 minutes).
Then I gave a try to CTRA race 1, installed Join2LFS and ... "Host has a different game code".
My guess is that CTRA provides Y18 server, and I appear to have a Y20 client (not sure about what it means, though). So do you reckon I should try to downgrade LFS to Y18 ? (not sure about how to to that either ...).
As for the last comment, I will probably upgrade to S2 in a few days/weeks, after a quick look at BrowseForSpeed the number of avalaible server is certainly huge compared to S1. It's a pity one can't benefit from the S1 version (since LFS is definitely so much more a multiplayer game than a solo one).
I understand this has nothing to do with the makers of the game (and much with the whole community switching to S2), but then what's the point in selling S1 if it's not worth playing ?
Luckily it's not more expensive to upgrade to S1 then to S2 than to go directly for S2.
Anyway, many thanks agains for your help !