502 Bad Gateway: nginx/1.14.2

I need to deploy an app in my university VPS, the admin gave me an access and the domain. But when I need to setup Nginx, there was several issue.

Installed Package

1. Nginx: nginx version: nginx/1.25.1
2. PHP: PHP 7.4.33 (cli) (built: Jun 9 2023 16:51:37) ( NTS )

System Run : Nginx

root       41300  0.0  0.1   9728   888 ?        Ss   17:39   0:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
nginx      41302  0.0  0.6  10392  3332 ?        S    17:39   0:00 nginx: worker process
root       41660  0.0  0.1   3240   648 pts/3    S+   17:50   0:00 grep nginx

* nginx.service - nginx - high performance web server
     Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
    Drop-In: /etc/systemd/system/nginx.service.d
             `-override.conf
     Active: active (running) since Tue 2023-07-25 17:39:06 UTC; 21min ago
       Docs: https://nginx.org/en/docs/
    Process: 41299 ExecStart=/usr/sbin/nginx -c /etc/nginx/nginx.conf (code=exited, status=0/SUCCESS)
    Process: 41301 ExecStartPost=/bin/sleep 0.1 (code=exited, status=0/SUCCESS)
   Main PID: 41300 (nginx)
      Tasks: 2 (limit: 23892)
     Memory: 3.4M
        CPU: 45ms
     CGroup: /system.slice/nginx.service
             |-41300 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
             `-41302 nginx: worker process

Jul 25 17:39:05 pascasarjana systemd[1]: Starting nginx - high performance web server...
Jul 25 17:39:06 pascasarjana systemd[1]: Started nginx - high performance web server.

System Run : PHP-FPM

root       41332  0.0  3.0 193472 15916 ?        Ss   17:42   0:00 php-fpm: master process (/etc/php/7.4/fpm/php-fpm.conf)
www-data   41333  0.0  1.2 193856  6468 ?        S    17:42   0:00 php-fpm: pool www
www-data   41334  0.0  1.2 193856  6468 ?        S    17:42   0:00 php-fpm: pool www
root       41822  0.0  0.1   3240   640 pts/3    S+   17:57   0:00 grep php-fpm

The Problem

I installed nginx v1.25, but the system says that nginx for domain is nginx v.1.14. Was the admin give me wrong proxy?

source https://stackoverflow.com/questions/76765450/502-bad-gateway-nginx-1-14-2