Next.js App Router — Sidebar Link 2nd-Visit Stall Repro

Open this page behind a reverse proxy (Coolify Traefik, Vercel edge, or any production-grade proxy with HTTP/2 + TLS).

1. Click Page A in the sidebar — fast (~80ms URL commit).
2. Click Page B — fast.
3. Click Page C — fast.
4. Click Page A again — URL never commits within 20s. Window stays on Page C.

Bug reproduces on next@16.2.2, 16.2.6 (stable), and 16.3.0-canary.21.

Does not reproduce on next build && next start against localhost (no proxy, HTTP/1.1).