Did you use apt or yum to install nginx? Check the website logs to see if there are access records? Is accessing using the browser's incognito mode the same?
Is the visited domain name added to the website?

aaP_wwnsugianto

    Hello, the nginx/apache aapanel installed using the apt command cannot manage the website added using aapanel.
    You need to stop it and install nginx using aapanel
    Are the latest access records in the log at your time?

    aaP_wwnsugianto