I am assuming, the request made by the HTTP connector is returning a good amount of data which requires chunking. According to this documentation, the endpoint which you are sending the request to, needs to send partial data which would enable HTTP connector to use chunking to download the whole data.
To download chunked messages from an endpoint over HTTP, the endpoint must support partial content requests, or chunked downloads.
Logic Apps can't control whether an endpoint supports partial requests. However, when your logic app gets the first "206" response, your logic app automatically sends multiple requests to download all the content.
Also, this might be helpful. I came across this thread, while facing a similar problem in the SFTP connector.