Two sites listening on same port simultaneously with different location (context) not workig

[svgkraju]

I installed gitlab in behind nginx reverse proxy and it worked fine. Added
the below configuration. Note that location path was changed.

upstream gitlab-workhorse {
  server unix:/var/opt/gitlab/gitlab-workhorse/socket;
}

server {
  listen 0.0.0.0:80 default_server;
  listen [::]:80 default_server;
  server_name abcd.com; 
  server_tokens off;
  root /opt/gitlab/embedded/service/gitlab-rails/public;
  access_log  /var/log/nginx/gitlab_access.log;
  error_log   /var/log/nginx/gitlab_error.log debug;

  location /gitlab {
    client_max_body_size 0;
    gzip off;
    proxy_read_timeout      300;
    proxy_connect_timeout   300;
    proxy_redirect          off;
    proxy_http_version 1.1;
    proxy_set_header    Host                $http_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;
    proxy_pass http://gitlab-workhorse;
  }
}
While testing gitlab, I deleted default file soft link from nginx
sites-enabled.

I created the soft link again the configuration is as follows: Note that
default_server is removed her and location path is "/"

server {
  listen 0.0.0.0:80;
  listen [::]:80;
  root /var/www/html;
  index index.html index.htm index.nginx-debian.html;
  server_name _;
  access_log  /var/log/nginx/default_access.log;
  error_log   /var/log/nginx/default_error.log debug;
  location / {
    try_files $uri $uri/ =404;
  }
}

Now while accessing my VM ip http://x.y.z.a, I am getting "403 Forbidden"
error in the browser. However gitlab still working. How to get both the
sites working listening on port 80 but with different context of location?

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,287036,287036#msg-287036