A platform keeps WebSockets behind ingress plus an edge proxy and only one upgraded route returns 400.
One ingress route still breaks WebSocket upgrades because Host handling drifts across proxy layers
Normal HTTP routes work, but one upgraded path fails because the Host and Upgrade semantics are not aligned end to end.
Scenario
What to check first
- Identify the primary failure signal in the WebSocket Host Boundary scenario.
- Separate visible symptoms from the underlying technical dependency.
- Describe the safest recovery path and the follow-up prevention work.
Checking checklist
- Summarize the current impact and the last known change.
- Collect direct evidence from logs, runtime state, and configuration before changing anything.
- Separate immediate recovery from permanent prevention work.
Recovery and prevention
Trace Host and Upgrade headers across every layer before touching app code.
Questions worth viewing together
Community-field ingress problem inspired by Stack Overflow patterns where WebSocket upgrades failed because Host and proxy headers drifted. A passing health check does not prove upgraded traffic sees the same header surface.
Teams often tweak timeouts when the handshake is invalid before the backend sees it.
WebSocket success depends on header continuity across every proxy layer.
Similar cases seen in the field