As a Mexican, do I need a visa if one stop of my flight is in Shenzhen?

I travel from LAX to Sydney and my flight makes two stops, first in Shenyang (7hrs wait) and the second one in SZ (2hrs wait) before the flight to Sydney. I´ve read that in Shenyang you don´t need a visa and you can stay up to 24hrs, but i want to know if i need a visa to enter SZ, stay there for 2 hrs and then leave to Sydney.

Thank you and I really look forward to get your answer.

Rebeca