'This site can't be reached' in Chrome means a connection couldn't be established. Here's how to identify the specific cause and fix it quickly.
That site is down, or your DNS can't resolve it.
Next step: Check downdetector.com for reports. Try pinging the domain in Command Prompt: ping sitename.com. If it times out for everyone, the site is down.
Your internet connection or DNS has failed.
Next step: Restart your router. Then open Command Prompt and run: ipconfig /flushdns — followed by: ipconfig /renew — to reset your network connection.
Chrome's network stack or cache is corrupted.
Next step: Open an Incognito window (Ctrl+Shift+N) and test. If it works, clear Chrome's cache: Settings → Privacy and security → Clear browsing data.