Explore the guide library · Browser and DNS help
Use the pattern of certificate failures and the Mac’s date and time to decide where the problem belongs.
If several secure websites suddenly report certificate problems on one Mac, inspect its date and time before changing router settings. Certificate validity depends partly on time. A substantially incorrect clock can make otherwise valid certificates appear outside their allowed period.
Record the pattern
Note the browser’s exact message and whether the failure affects one site or many unrelated sites. Compare another device using the same network. Avoid entering credentials or payment details into a page while its identity cannot be verified.
Check the Mac’s clock
Apple includes correct date and time among its Wi-Fi internet troubleshooting checks. Inspect the displayed date, time and time zone and use the supported settings to correct an actual error. On managed equipment, let the administrator resolve restrictions or repeated synchronization failures.
Retry the exact hostname
After the clock is correct, revisit the intended address from a trusted bookmark or the organization’s official link. A certificate issued for one hostname may not validate a different address, even when both appear to reach related content.
Interpret what remains
- One site fails on several devices: the site owner may need to repair its certificate or configuration.
- Many sites fail only on this Mac: investigate its software and trust configuration.
- Failures appear only on one network: ask its administrator about the connection path.
Preserve the protection
Do not mark an unknown certificate as permanently trusted, install a random certificate profile or disable validation to remove the warning. Those actions can conceal the very identity problem the browser is reporting.
If the warning persists, provide support with the public hostname, message and timing, excluding private browsing details. The goal is a normal trusted connection after a verified correction. The disappearance of the warning after a bypass would not establish that the original security problem had been solved.
Sources and editorial notes
Sources checked 8–9 October 2026. Independent guidance and original illustrations; product comparisons use published specifications rather than hands-on benchmarks. Check the exact model, revision and regional documentation before changing settings.