Websockets not working with fastproxy option

[Silenoz93]

Welcome!

• [x] Yes, I've searched similar issues on GitHub and didn't find any.
• [x] Yes, I've searched similar issues on the Traefik community forum and didn't find any.

What did you do?

Hi, I changed my config to use the new fastproxy option but websockets do not seem to work. I am using Immich and Homeassistant. I can access both services, but I get strange logs in Homeassistant and Immich tells me the server is offline.

When deactivating the fastproxy option, everything is working as expected.

What did you see instead?

Access Log for Immich: 400 Bad Request "GET /api/socket.io/?EIO=4&transport=websocket HTTP/1.1" 400 37 "-" "-" 470 "media-immich-api@docker" "http://172.30.0.5:2283" 2ms

Nothing found in Access Logs for Homeassistant. Home Assistant logs: WARNING (MainThread) [aiohttp.websocket] Client protocols [''] don’t overlap server-known ones ()

What version of Traefik are you using?

v3.2.1

What is your environment & configuration?

fastProxy: {}

If applicable, please paste the log output in DEBUG level

No response

[nmengin]

Hey @Silenoz93,

Thanks for the bug report.

We have put it on our (maintainer) plate to reproduce. We'll keep you updated on this ticket once we have moved froward on it.

[kevinpollet]

Closed by #11522