Something's seriously broken with French train itineraries, don't know if on DB's or SNCF's side:
I tried to check connections in DB Navigator from Paris Gare d'Austerlitz to Antibes in fall this year.
This is one of many connections Navigator proposes:

Paris Austerlitz -- ~1h -- Chartres -- ~1h -- Paris Montparnasse -- ~5h30 -- Antibes

There's another one via Orléans 😲

Any ideas, @jon ?