When you go to mainland China You really need VPN at least if you can read Mandarin properly!!!
Otherwise, You better to prepare a VPN - Virtual Private Network - 仮想専用線 with Wi-Fi Router is the BEST !!!
But at least if you have a VPN account which you can use it in Mainland China then you will be fine
You could use Goole, Facebook, WhatsApp and all !!!
And here this site is one of the best
Pronto VPN
Get a VPN account then
Keep on Rock No matter what !!!