DNS - Domain Name System

DNS

DNS controls your domain name's website and email settings. When visitors go to your domain name, its DNS settings control which company's server it reaches out to.

"Server not found" issues can be rectified by changing the DNS setting to a different DNS rather than using the supplied by your service provider.

Example of DNS: 208.67.222.222

or Google: 8.8.8.8

See OpenDNS for further details:
https://www.opendns.com/home-internet-security/

Finding a fast DNS can be done via software such as Namebench: https://code.google.com/archive/p/namebench/