Intermittent 500/502 from CDN while origin returns 200 on mp3 requests

Hello,

We serve public mp3 files from a DigitalOcean Space (fra1) with CDN enabled. The files are consumed by a Unity WebGL app (Unity 2022.3.69f1) that preloads and plays many voice clips via UnityWebRequestMultimedia.GetAudioClip. We use Sentry to capture errors.

Even before enabling origin logs, we saw intermittent 500/502 on some mp3 requests. After enabling Spaces origin logging, we observed that the origin replies 200 while the client sometimes receives 500/502 from the CDN. These errors are rare compared to the total volume of mp3 downloads, and not always on the same files.

Concrete origin log example:

[10/Jan/2026:14:23:47 +0000] 172.69.151.18 - tx00000af6d21948dbd738e-00696260f3-1ae3d551-fra1c s3:GetObject /StreamingAssets/Voices/fr/Theory/Chapter4/Theory4_0_answer1_Explanation.mp3 "GET /StreamingAssets/Voices/fr/Theory/Chapter4/Theory4_0_answer1_Explanation.mp3 HTTP/1.1" 200 - 53184 - 6 6 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/143.0.0.0 Safari/537.36" - - - ECDHE-RSA-AES128-GCM-SHA256 - fra1.digitaloceanspaces.com TLSv1.2 - -

At the same time, Sentry reported a 502 on that URL. This suggests the edge CDN returned 500/502 while the origin served 200.

Any idea or advice on how to fix that?

Thanks in advance.