How to troubleshoot a failed Consul server node and verify recovery steps

When a Consul server node becomes unreachable, the cluster marks it as failed and updates the service catalog. What systematic steps should an operator take to confirm the failure, distinguish it from a network partition, and safely restore the node? Include which Consul CLI commands to run, how to interpret logs and health checks, and what actions to perform if the node needs to be forced out or re‑joined.