websockets server: 401 unauthorized

[UltraBlackLinux]

Describe the bug
Exposing vscode-server (uses websockets for initialization) through this listener just returns 401 unauthorized for all websocket handshakes (according to a webkit browser, firefox doesn't show this kind of info).

I have no idea how to even approach debugging this. It's sadly quite an annoying setup to begin with, due to the way docker works. Caddy shouldn't interfere, since it's working fine without my proxy in front.

To Reproduce
Set the project up according to the readme and make it accessible through caddy, or another reverse-proxy (required for this whole thing to work) and put vscode-server behind the poco proxy

Logs

container-power-proxy  | client -> server (length=104, flags=0x82).
container-power-proxy  | cl I/O error: Operation now in progress # I don't think these errors change anything. Simply returning the data sent from the client also returns the same error
container-power-proxy  | server -> client (length=104, flags=0xc2).
container-power-proxy  | sv I/O error: Operation now in progress
container-power-proxy  | client -> server (length=0, flags=0x0).

Please add relevant environment information:

• Arch Linux 6.7.9-zen1-1-zen
• POCO 1.12.5p2
• linuxserver/code-server:4.22.0, caddy:2.7.6