Nginx Upstream and Routing

default

upstream s {
    server 127.0.0.1:3000;
}

upstream backend {
    server 127.0.0.1:5051;
}
server {
    listen 80;
    listen [::]:80 ipv6only=on default_server;
    listen 443 ssl http2 default_server;
    listen [::]:443 ssl http2 default_server;

    server_name server_domain_or_IP;
    include snippets/self-signed.conf;
    include snippets/ssl-params.conf;

    root /var/www/html;
    index index.html index.htm index.nginx-debian.html;

    #server_name _;
    location / {

        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        X-Forwarded-Proto $scheme;

#        rewrite ^/api/?(.*) /$1 break;
        proxy_pass http://s;

#        proxy_redirect off;
#        proxy_set_header Upgrade $http_upgrade;
#        proxy_set_header Connection 'upgrade';
#        proxy_set_header Host $host;
#        proxy_cache_bypass $http_upgrade;
#        try_files $uri $uri/ /index.html =404;

    }

    location /api {

        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        X-Forwarded-Proto $scheme;

        rewrite ^/api/?(.*) /$1 break;
        proxy_pass http://backend;

#        proxy_redirect off;
#        proxy_set_header Upgrade $http_upgrade;
#        proxy_set_header Connection 'upgrade';
#        proxy_set_header Host $host;
#        proxy_cache_bypass $http_upgrade;
#        try_files $uri $uri/ /index.html =404;

    }

#    location / {
#        try_files $uri $uri/ /index.html =404;
#    }

}