When the server restarts, Nginx appears to be running but it's not serving any requests. When I restart Nginx, it still doesn't work. However, when I check through the terminal:
sudo netstat -tulpn | grep :80
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 279/nginx: master p
tcp6 0 0 :::80 :::* LISTEN 279/nginx: master p
When I use the command 'sudo pkill nginx' in terminal and restart Nginx, everything works properly:
sudo netstat -tulpn | grep :80
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 2116/nginx: master