Record the symptom first
Write down the exact URL, the browser message and the time. Try another network or device to tell a local problem from a general one. A site that won't open, a site that returns a server error and a site that opens with a warning are three different situations.
Don't send passwords together with a screenshot of the problem. The URL and symptoms are enough for a first diagnosis; access is shared with the person responsible separately.
DNS is not your website's content
DNS records say where a request should go. Email may have its own records and a different provider. So changing where your website points doesn't mean replacing the whole zone. This matters most when moving to a new host.
Cloudflare's documentation on DNS records shows that records are managed individually by type and purpose. Before editing anything, save the current values and note the reason for each change.
An HTTPS warning needs its own check
Check that the certificate matches the domain, that it hasn't expired, and how the server is configured. Don't tell visitors to ignore the warning as a permanent fix. Once it's fixed, test the main address and every redirect variant. Add the certificate's expiry date to your monitoring.
With website hosting, decide in advance who is responsible for domain settings and the certificate. Technical support can narrow down the cause and make the right change without breaking other services.
