Does accessing your router page via caddy work when you’re actually on your home network

Unfortunately no, which rules out an issue with wireguard.

Have you tried a different web browser to rule out your LLM suggested cookie issues

It’s not the stale cookie issue which goes away when opening a website in incognito. I think it expects the cookie to have the original host information.

Let me paste the list of issues the LLM mentioned. The following section is from the LLM

<LLM>

1. The router’s web UI expects the original hostname (e.g., 192.168.0.1) and builds redirects or CSRF tokens based on it. Caddy sends its own host (myproxy.example.com).
2. Authentication cookies are set for the original domain and may be dropped or rewritten by the proxy, causing the server to think the user is unauthenticated.
3. The router returns Location: 192.168.0.1… which points the browser back to the internal address, bypassing the proxy.
4. Tokens are generated using the Origin or Referer header; the proxy changes these, making the token invalid on POST.
5. The router forces HTTPS or blocks HTTP when it sees a mismatch, and Caddy may be terminating TLS while the upstream expects plain HTTP.
6. Some admin UIs use WebSocket for status updates; if Caddy doesn’t forward the upgrade, the page may reload to the login screen.
7. The router’s UI may be served from / but expects relative paths; Caddy’s uri rewrite can break those links.

</LLM>

It has also mentioned some solutions for each cause. But I don’t want to blindly apply them without knowing what is wrong.