# Restore access to a SQL endpoint

An inaccessible endpoint can fail before SQL is received. Test from the affected client host and keep the exact address, port and error. A successful connection from localhost does not prove that a remote application can reach the same listener.

## Find the failing layer

Check that the hostname resolves to the expected destination and that the configured native or HTTP port is reachable. Confirm `listen_host` and any command-line address override on the server. HTTP is optional and is disabled when `http_port` is omitted.

For HTTP, test `/ping` before an authenticated query. A 401 response indicates credential failure. A 403 can indicate an Origin/Host restriction. A 503 can indicate admission or locking pressure. Capture the query identifier and exception code when a SQL response includes them.

## Avoid unrelated changes

Do not rotate credentials to fix a refused TCP connection or raise query memory limits to fix DNS. Check each stage independently. Configuration-file edits require a restart, so verify the file path used by the running process before applying a change.

There is no hosted account state or recovery console in the documented Coordinator DB interface. Use the deployment's process and network tools for a stopped host or blocked route.

See [HTTP status codes](https://coordinatordb.com/docs/concepts/features/interfaces/http), [configuration files](https://coordinatordb.com/docs/concepts/features/configuration/server-config/configuration-files) and [connection limits](https://coordinatordb.com/docs/concepts/features/configuration/settings/tcp-connection-limits).