Transit Visa inquiry

Hi there,

I am planning a trip to South Korea via 2 cities which are Guangzhou and Dalian in China.
I would be a transit passenger.
I would be in Guangzhou airport for about 4hrs for the next flight to Dalian and also would be in Dalian airport for about 7hrs for the next flight to South Korea.
I just want to confirm whether I need transit Visa for this flight route.

Thank you