This is a common error when your firewall, web server, or network has not been configured correctly with SSL.
- Your SSL certificate needs to be installed for the correct website.
- Also ensure your private key has not been deleted, or is not corrupt.
- Assign port 443 as the SSL port on the Web Server, and also check is this is port is not blocked with a router or firewall.
- Check your DNS settings on the network as well.