Hello @jupiter
I would think that it could be a regional issue due to network control that China implements. Can you please confirm if you are able to access https://community.mattermost.com from your end with and without the VPN?
Did you check with your network administrator if there is any firewall that’s blocking the connection from China as well?
If your Mattermost server is publicly hosted, send me the URL through a direct message so I can test it on my end too.