fix: Fixed api url on web

docs/reference/troubleshooting.md

@@ -20,6 +20,13 @@ or is not 64 hex characters.
 
 ## Nobody can sign in
 
+**Every request 404s and the interface loads fine.** Your reverse proxy sends
+the whole hostname to `web:3000`. `/api`, `/auth`, `/public`, `/install*` and
+`/update*` belong to `server:8080` and the web app forwards nothing — see
+[Ports and networking](./ports-and-networking.md#reverse-proxy-notes). The
+tell is `curl -si https://<your-host>/auth/bootstrap-status` returning HTML
+with `x-powered-by: Next.js` instead of JSON.
+
 **`/setup` appears when users already exist.** The server is pointed at a
 different database than you think. Check the database name in `MONGO_URI`,
 which is taken from the end of the URI.
@@ -169,6 +176,11 @@ is `<your-instance>.vantage.<yourdomain>/status/<page-id>`, the same
 per-instance subdomain everything else in Vantage uses. A wrong or missing
 subdomain resolves to no instance at all, which is also a 404.
 
+Third possibility: `/public` is not routed to the server. Check with
+`curl -si https://<your-instance>.vantage.<yourdomain>/public/status/<page-id>`
+— JSON is correct, HTML carrying `x-powered-by: Next.js` means the proxy sent
+that prefix to the web app.
+
 **Loads, but shows an explanation instead of components.** This is not a
 fault — it is the page working as designed. It means either the licence has
 lapsed (a self-hosted instance past its grace period, or a cloud instance