[Bug]: "Failed to fetch remote auth endpoint" error when trying to connect to headless remote server

[aspiers]

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/desktop

Steps to reproduce

1. Set up a remote VPS with access over Tailscale
2. Run npx t3 server --host "$(tailscale ip -4) on the VPS
3. Try to add the environment via the pairing URL in the T3Code desktop app:
   

Expected behavior

It should accept the URL and add the remote environment.

Actual behavior

It gives the error Failed to fetch remote auth endpoint http://100.x.y.z:3773/.well-known/t3/environment (Failed to fetch).

However, the same URL is accessible from the same desktop via curl and the browser, proving it's not a network / firewall issue.

Impact

Major degradation or frequent failure

Version or commit

0.0.17

Environment

openSUSE Tumbleweed Linux

Logs or stack traces

No new log lines appear in any of `~/.t3/userdata/logs/*.log` when I click "Add Backend".

Screenshots, recordings, or supporting files

No response

Workaround

No response

[fzimmermann89]

Similiar issue trying to connect to WSL. The server part gets the request and logs a 200 response:

[22:47:11.373] INFO (#159) http.span.41=0ms: Sent HTTP response
  http.method: GET
  http.url: /.well-known/t3/environment
  http.status: 200

[sazzy4o]

I get the same issue. If you don't care about the desktop app, the browser UI worked for me after I copied the Pairing URL and paste it into into my browser