Identifying the problem
In most cases, every website stores information about the errors that occur when it is accessed and a visit’s details (the address it was accessed from, how many times, what browsers were used, etc.). All of this information is stored in the server’s log files.
If the site does not open, log in to the server and view the information about the website errors in the log file. It is stored in different places on the hard disk in each operating system:
Log file of website errors
FreeBSD: /home/httpd-logs/<your_site>.error.log Debian/Ubuntu/Centos: /var/www/httpd-logs/<your_site>.error.log
Log file of Apache errors
FreeBSD: /var/log/httpd-error.log Debian/Ubuntu: /var/log/apache2/error.log Centos: /var/log/httpd/error_log
Log file of Nginx errors
FreeBSD:/var/log/nginx-error.log Debian/Ubuntu/Centos: /var/log/nginx/error.log
The “Server Not Found” Error
A possible reason for such an error is that a user does not get redirected to the web site’s IP address by its domain name. This occurs due to DNS problems, you will need to perform diagnostics of the nameserver.