Diagnose Gateway Error

Triage by Symptom

Symptom	First Check	Invoke Skill
5xx errors on all requests	Upstream connectivity, spec.address binding	`omni-gateway-config`
4xx errors (auth/policy)	PolicyBinding targeting, policy config	`omni-gateway-config`
Gateway unreachable / port not responding	Listen address (0.0.0.0 vs localhost), port conflicts	`omni-gateway-config`
Policy not applying	PolicyBinding → ApiInstance cross-reference	`omni-gateway-config`
`upstream connect error` / connection refused	Upstream service health, routes config	`omni-gateway-logs`
TLS handshake failures	Certificate validity, TLS config in conf.d	`omni-gateway-logs`
`xDS disconnected` / control plane errors	Anypoint connectivity, registration token validity	`omni-gateway-logs`
STARTED state never reached	Registration artifact, conf.d correctness	`omni-gateway-install` (re-register), then `omni-gateway-config`
Known-good config still failing	Live deployed state may differ from conf.d	`omni-gateway-dump`