How do you troubleshoot a 404 'page not found' response in Traefik when the backend is healthy?

A 404 from Traefik itself (not the backend) almost always means no router matched the request, so the first step is checking the dashboard's Routers view to confirm the expected router even exists and is in a success state rather than showing a provider error.

Next, verify the rule syntax against the actual request: a typo in Host, a missing backtick, or using Path where PathPrefix was intended will all cause a router to simply never match, with no error logged, since "rule didn't match" is expected, ordinary behavior from Traefik's point of view.

Check that the router is attached to the entrypoint the client actually connected on; a router only bound to websecure won't respond on the plain web entrypoint at all.

Finally, for label- or annotation-based configuration, confirm the provider actually picked up the resource, since a missing traefik.enable=true label, a typo in a Kubernetes annotation, or the container being on a network Traefik doesn't watch will all silently prevent the router from being created in the first place.