nginx config:

server
{
listen 80;
listen [::]:80;
server_name whatsapp.yelobee.com;
index index.html index.htm default.htm default.html;

root /www/wwwroot/whatsappchat/backend;

#SSL-START SSL related configuration
#error_page 404/404.html;
	#SSL-END

#ERROR-PAGE-START  Error page related configuration
#error_page 404 /404.html;
#error_page 502 /502.html;
#ERROR-PAGE-END


#REWRITE-START Pseudo-static related configuration
include /www/server/panel/vhost/rewrite/node_backend.conf;
#REWRITE-END

#Files or directories forbidden to access
location ~ ^/(\.user.ini|\.htaccess|\.git|\.svn|\.project|LICENSE|README.md|package.json|package-lock.json|\.env|node_modules) {
    return 404;
}

#One-click application for SSL certificate verification directory related settings
location /.well-known/ {
    root  /www/wwwroot/whatsappchat/backend;
}

# HTTP reverse proxy related settings begin >>>
location ~ /purge(/.*) {
    proxy_cache_purge cache_one $host$request_uri$is_args$args;
}

location / {
    proxy_pass http://149.28.129.16:7500;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header REMOTE-HOST $remote_addr;
    proxy_connect_timeout 30s;
    proxy_read_timeout 86400s;
    proxy_send_timeout 30s;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
}
# End of HTTP reverse proxy related settings <<<

access_log  /www/wwwlogs/backend.log;
error_log  /www/wwwlogs/backend.error.log;

}

backend.error.log:

2024/01/19 17:46:18 [error] 28180#0: *1702 connect() failed (111: Connection refused) while connecting to upstream, client: 202.190.124.183, server: whatsapp.yelobee.com, request: "GET / HTTP/2.0", upstream: "https://149.28.129.16:7500/", host: "whatsapp.yelobee.com"
2024/01/19 17:51:41 [error] 28333#0: *1705 connect() failed (111: Connection refused) while connecting to upstream, client: 202.190.124.183, server: whatsapp.yelobee.com, request: "GET / HTTP/2.0", upstream: "https://127.0.0.1:7500/", host: "whatsapp.yelobee.com"

backend.log:

192.155.88.231 - - [19/Jan/2024:17:45:46 +0800] "*1" 400 150 "-" "-"
172.104.11.46 - - [19/Jan/2024:17:45:55 +0800] "GET / HTTP/1.1" 302 138 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 13_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/108.0.0.0 Safari/537.36"
202.190.124.183 - - [19/Jan/2024:17:46:18 +0800] "GET / HTTP/2.0" 502 552 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"
202.190.124.183 - - [19/Jan/2024:17:51:41 +0800] "GET / HTTP/2.0" 502 552 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"