if you get /cgi-sys/defaultwebpage.cgi redirect on fresh Magento 2 CMS installation, try this url: yourdomain/index.php (type index.php manually).
Or clear your browser cache, you will be able to open your domain without getting redirected to this /cgi-sys/defaultwebpage.cgi page
Or read this article : Fix for Domain Redirecting To /cgi-sys/defaultwebpage.cgi Page