In Safari:
I'm in china. Is App Store Connect under repair or sth? Can't connect to the website
There is no issue reported on AppstoreConnect.
Did it ever work before ? Since when do you have problem ?
May be this old thread could help: https://discussions.apple.com/thread/7996819
You are unable to access the Chinese App Store because you do not have an account in that store. To have an account, you would need to be physically located in China, have a credit card issued by a bank in China, and have a billing address in China. If you don't have that, you cannot access the Chinese store.