A four‑agent reverse‑engineering effort using Claude, Codex, Gemini and locally hosted open‑weight models (Qwen/Hermes) dissected the firmware of a 2026 TP‑Link Deco XE75 Pro V3 mesh router in a single afternoon, uncovering how to add per‑SSID IoT VLAN tagging that TP‑Link omitted. The team relied on the open‑weight models after Opus 4.8/5.5 became unusable due to restrictive filter rules, enabling them to patch the feature directly into the firmware.