Invalid credentials both on internal IP and external URL #85

Describe the bug
Cannot add instance with credentials

To Reproduce
Steps to reproduce the behavior:
Dunno if it's reproductible on any setup, but on mine it is.
qbittorrent is running on a VM (let's call it B), running on my physical host (let's call it A).
qbitwebui is running on A, and whether I try using traefik's URL also running on A, or directly using B's IP with exposed port, I'm getting an invalid credentials
Logs state the same thing with no more details :
qbitwebui-1 | [2026-05-18T09:21:49.490Z] [ERROR] qBittorrent proxy failed for instance 2: Invalid credentials
qbitwebui-1 | [2026-05-18T09:21:49.491Z] [ERROR] qBittorrent proxy failed for instance 2: Invalid credentials
qbitwebui-1 | [2026-05-18T09:21:49.491Z] [ERROR] qBittorrent proxy failed for instance 2: Invalid credentials

Of course I'm sure the credentials are good because I'm using them to login to the webUI.

Expected behavior
Instance to be added.

Screenshots

Desktop (please complete the following information):

• OS: Windows 11
• Browser Firefox
• Version 150.0.3

Additional context
I can add the interface if I add the IP in the whitelist, but as the server has the same IP as my traefik, I am then opening the URL to the whole internet, which can lead to pretty much anything.