Hi @dangdh, welcome to the community!
I am sorry you are having trouble.
Starting with version 1, n8n uses websockets to send status updates from the server to the UI. For these to work your nginx config needs a few more tweaks. Check out "Connection Lost" warning - #7 by Valerian_Lebert for an example, from the looks of it I think these two lines need to be added to your server block:
proxy_set_header Connection 'upgrade';
proxy_set_header Upgrade $http_upgrade;