Indeed, the French transportation network is organised very centrally around Paris.

Looking at the map of the recent (it might change rapidly) intercity bus connections provided by comparabus.com (some website to book buses) and the train network maps provided by the SNCF for Intercités and TGVs, it looks clear that most trains and buses are centered around Paris (you might find a connection in Tours or Le Mans) so in any case you will have to connect.

An alternative would be ride sharing. Blablacar is the most popular service. A search for this weekend shows few direct Rennes-Poitiers trips though. Also know that ride share trips tend to appear only about 2 weeks before the date of travel, so if you want to secure a trip early, this might not be your best option.

Most French people now compare trains, buses and ride sharing options (and planes for the longer distances) when travelling across the country.

Indeed, the French transportation network is organised very centrally around Paris.

Looking at the map of the recent (it might change rapidly) intercity bus connections provided by comparabus.com (some website to book buses) and the train network maps provided by the SNCF for Intercités and TGVs, it looks clear that most trains and buses are centered around Paris (you might find a connection in Tours or Le Mans) so in any case you will have to connect. Using regional trains and avoiding Paris is possible but probably longer and less convenient, going through Nantes.

An alternative would be ride sharing. Blablacar is the most popular service. A search for this weekend shows few direct Rennes-Poitiers trips though. Also know that ride share trips tend to appear only about 2 weeks before the date of travel, so if you want to secure a trip early, this might not be your best option.

Most French people now compare trains, buses and ride sharing options (and planes for the longer distances) when travelling across the country.