2 layovers

Hello,

As I can't find any information on what to do if you have a layover in 2 cities of China. This is our route:

Brussels - Shanghai - Shenzhen - Cairns

Nationalities are Belgian and Australian

We have a 6.5 hour stopover in Shanghai and a 8.5 hour stopover in Shenzhen. We will not be leaving the airport, as I'm scared of not being able to get back in.

Do we need to request a visa beforehand to be able to board all of our flights? Or will we be able to get a free transit upon arrival? *slight panic* We are leaving this Friday and I only found out about this now.

Thank you for your reply!

Natalia