The gray code under “This site can’t be reached” tells you which half of the problem you’re in

The "This site can't be reached" page in Chrome and Edge looks the same for very different failures. The useful part is the gray code printed underneath, because it tells you which half of the problem you're in.

• DNS_PROBE_FINISHED_NXDOMAIN or ERR_NAME_NOT_RESOLVED: the domain never resolved to an IP. Check the URL, flush your DNS cache, or try a public resolver like 1.1.1.1 or 8.8.8.8.
• ERR_CONNECTION_TIMED_OUT or ERR_CONNECTION_REFUSED: the address was found, but nothing answered. That points at the server or a firewall.

Before changing anything, load the site on a different network, like your phone on mobile data. If it works there, it's your device or connection. If it fails everywhere, only the site owner can fix it.

On the owner side, the usual cause is undramatic: a memory spike kills the database process, and the site stays down until someone notices. On ScalaHosting's managed plans, SPanel checks services every five minutes and restarts anything that has stopped.

The guide has the exact commands for Windows, Mac, and mobile, plus a server-side checklist: https://www.scalahosting.com/blog/this-site-cant-be-reached/