A monitor is only marked down after it fails several checks in a row (two by default). On paid plans a second location must agree before an alert goes out. This stops one-off network hiccups from waking you up.

Open the monitor to see the exact error, the HTTP status code and how long the response took. Common causes:

• Timeout: the server took longer than the timeout to answer.
• SSL problem: the certificate is expired or does not match the name.
• 5xx error: the application crashed or the server is overloaded.
• Keyword missing: the page loaded but the expected text was not on it.

If your firewall blocks unknown visitors, allow our checker in your security plugin or host panel.