I had made few changes. Have a look into them

nginx.conf

@@ -0,0 +1,90 @@
+
+#upstream app_nodejs {
+#  server 127.0.0.1:3000;
+#}
+
+
+server {
+	listen 80 default_server;
+	listen [::]:80 default_server;
+
+	# SSL configuration
+	#
+	# listen 443 ssl default_server;
+	# listen [::]:443 ssl default_server;
+	#
+	# Note: You should disable gzip for SSL traffic.
+	# See: https://bugs.debian.org/773332
+	#
+	# Read up on ssl_ciphers to ensure a secure configuration.
+	# See: https://bugs.debian.org/765782
+	#
+	# Self signed certs generated by the ssl-cert package
+	# Don't use them in a production server!
+	#
+	# include snippets/snakeoil.conf;
+
+	root /var/www/html;
+
+	# Add index.php to the list if you are using PHP
+	index index.html index.htm index.nginx-debian.html;
+
+	server_name 172.31.42.185;
+
+	location / {
+		 # First attempt to serve request as file, then
+		 # as directory, then fall back to displaying a 404.
+		 #try_files $uri $uri/ = 404;
+                 proxy_pass http://localhost:3000;
+        	 proxy_http_version 1.1;
+       		 proxy_set_header Upgrade $http_upgrade;
+        	 proxy_set_header Connection 'upgrade';
+        	 proxy_set_header Host $http_host;
+       		 proxy_cache_bypass $http_upgrade;
+                 proxy_set_header X-Nginx-Proxy true;
+	}
+
+	#location / {
+		# First attempt to serve request as file, then
+		# as directory, then fall back to displaying a 404.
+	#	try_files $uri $uri/ =404;
+	#}
+
+	# pass PHP scripts to FastCGI server
+	#
+	#location ~ \.php$ {
+	#	include snippets/fastcgi-php.conf;
+	#
+	#	# With php-fpm (or other unix sockets):
+	#	fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
+	#	# With php-cgi (or other tcp sockets):
+	#	fastcgi_pass 127.0.0.1:9000;
+	#}
+
+	# deny access to .htaccess files, if Apache's document root
+	# concurs with nginx's one
+	#
+	#location ~ /\.ht {
+	#	deny all;
+	#}
+}
+
+
+# Virtual Host configuration for example.com
+#
+# You can move that to a different file under sites-available/ and symlink that
+# to sites-enabled/ to enable it.
+#
+#server {
+#	listen 80;
+#	listen [::]:80;
+#
+#	server_name example.com;
+#
+#	root /var/www/example.com;
+#	index index.html;
+#
+#	location / {
+#		try_files $uri $uri/ =404;
+#	}
+#}