Xiao Liu Lab

Nov 10, 2025 · Operations

Why a Healthy Frontend Still Returns 504 Errors: An MTU Mismatch Case Study

A production incident showed that despite flawless frontend health metrics and no logged errors, a subset of users experienced 504 Gateway Timeout errors caused by an MTU mismatch in the network path, highlighting the need for end‑to‑end connectivity checks beyond application monitoring.