All error codes

router_not_running

HTTP 409 The router must be running for this operation

What happened

The router is powered off. Attaching or detaching a network and rotating the management key are applied inside the running router, so a stopped one cannot accept them.

What to do

Start the router with POST /v1/servers/{id}/actions/power-on, wait for the task to finish, then repeat the same request with the same idempotency key.

Retrying

Change the state this refers to, then repeat the same request with the same idempotency key.

How it arrives

{
    "type": "https://docs.fiberax.com/errors/router_not_running",
    "title": "The router must be running for this operation",
    "status": 409,
    "code": "router_not_running",
    "request_id": "a277dcd1ca652c65"
}

Branch your code on code, never on the wording of title.