Travelling from Vientiane, Laos to Kunming, Kunming to Beijing, Beijing to Shanghhai, then Vancouver

Hi,
I have been confused of information sources about Direct Transit within 24 hours. I called the Embassy of China in Laos and they have confirmed we need a visa to transit in PRC if we are landing to any other cities in PRC but Beijing. But most of only sources say we fall into 24 hours Direct Transit when transit in PRC less than 24 hours. I and my friend (American and Lao Citizens) are travelling from Vientiane, Laos to Kunming, Kunming to Beijing, and Beijing to Shanghhai before our flight to Vancouver, Canada in mid September this year. Our transit and connected flights are about 19 hours in PRC and we do not plan to leave the airports. Much appreciate if you please tell me if we need a transit entry permit in our case? It's really confusing and we are not sure who we should believe.
Regards,
C&K