All error codes

router_rule_not_found

HTTP 404 Router rule not found

What happened

No rule or port forward with this number exists on the router. It was never created, or it has already been deleted - a repeated DELETE lands here too.

What to do

List the rules with GET /v1/servers/{id}/router/firewall-rules or GET /v1/servers/{id}/router/port-forwards and use a number from the list. If you were deleting, the rule is already gone.

Retrying

Fix the request and send it again.

How it arrives

{
    "type": "https://docs.fiberax.com/errors/router_rule_not_found",
    "title": "Router rule not found",
    "status": 404,
    "code": "router_rule_not_found",
    "request_id": "a277dcd1ca652c65"
}

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