One 502 among about 70 requests read steward@swarm critical at 1.4%: past the 30-request minimum and far past the 0.1% cutoff, yet one error. A new Settings → Thresholds field, "Fewest server errors to fail" (traefik.threshold.min_5xx, default 3), must also be reached in the 15-minute window; the 0.1% cutoff still catches a busy router. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>