Hello, thank you for reaching out!
It sounds like you're working with the Conversation API. Conversation API error codes are documented here; according to the documentation,
MEDIA_NOT_REACHABLE indicates that the link wasn't accessible from the Conversation API or the underlying channel.
However, given that another message was able to send successfully, and the server hosting the media was able to be hit by Postman, it may have been a momentary network or connection issue.
Regarding the timeout constraints and retry options, I'll follow up with the development team. We will add another response to this post with any additional information. Thank you again for reaching out!
Apologies for the delay in response here.
The timeout to retrieve media from the specified URL is 10 seconds. Naturally, the path that Sinch takes to retrieve the media from your URL may have higher latency than you experience locally, dependent on where the URL is hosted.
If you continue to experience the error, please do raise a support ticket via email@example.com and we will then be able to investigate further to see the Roundtrip time from the perspective of the media injection.