The server is delivering only part of the resource due to a range header sent by the client.
What does HTTP 206 mean?
The 206 Partial Content code is part of the 2XX class. This is a success code — the request was received, understood and processed successfully.
When is it used?
A server returns 206 Partial Content in situations matching the definition above. You will encounter it inspecting network requests, reading logs, or testing an API. Whether it signals a problem depends on its class: 2xx and 3xx are normal, while 4xx and 5xx usually need attention on the client or server respectively.