"This site can't be reached" or DNS errors
DNS_PROBE_FINISHED_NXDOMAIN and similar: the domain isn't pointing anywhere yet.
These errors mean the browser couldn't find an address for your domain.
- Check the domain hasn't expired with the WHOIS tool.
- Just registered the domain or changed nameservers? Wait: changes can take up to 24 to 48 hours. See Why DNS changes take time.
- Check the nameservers shown in WHOIS are the ones you expect (your hosting's, for example).
- Check the A record with the DNS checker: does it show your hosting or server IP address?
- Only on your device? Flush your DNS cache, or restart your router.
A newly added subdomain needs its own record too. See Creating a subdomain.