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Network L4 NETWORK-1492 · 10 min

A Cloudflare Tunnel stays up and WebSocket requests still fail because one origin path strips the Connection upgrade header after an internal rewrite

The tunnel is healthy, but a rewrite rule removes the upgrade context before the request reaches the origin.

NetworkFoundation OpsLevel 4Free10 min
Scenario

WebSocket apps fail only on one routed hostname behind Cloudflare Tunnel after origin rewrite rules were added.

What to check first
  • Identify the primary failure signal in the The Tunnel Stayed Open and the Upgrade Request Lost Its Secret Handshake While Passing Through the Hallway scenario.
  • Separate visible symptoms from the underlying technical dependency.
  • Describe the safest recovery path and the follow-up prevention work.
Checking checklist
  1. Summarize the current impact and the last known change.
  2. Collect direct evidence from logs, runtime state, and configuration before changing anything.
  3. Separate immediate recovery from permanent prevention work.
Recovery and prevention

Inspect rewrite and header preservation before blaming the tunnel connector.

Questions worth viewing together
Should I translate commands, logs, or product names?

No. Keep commands, logs, file names, APIs, and product names unchanged, then explain the reasoning in the selected UI language.

What should the answer focus on?

State the root cause, the evidence that supports it, and the safest recovery direction.

Why can the scenario remain in the original language?

The source scenario is treated as an incident artifact. Guidance, checklist, hints, and explanations can be localized around it.