In reply to fried:
If you scroll down the page a bit you'll see that 24 minutes of that are walking, to Gare de Lyon and from the station of Bois le Roi to Place de la République - you may have to expand the walking sections by clicking on a "+3 sign. The actual train ride is 32 minutes, and is apparently direct with no change.
On the other hand it seems to be a direct train when I try again on the other site now, so either there was a traffic problem yesterday when I first looked or I misread the info - something which is altogether possible! Whatever, 30 minutes to Font from the middle of Paris is pretty good for 8€10 each way.