[BUG] WebUI keeps losing connection to server

[RastaTaz]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

When deploying docker stack via compose (yml file in git repo, pulled ans deployed by portaainer) and using traefik as HTTP reverse proxy (bringing in TLS), the WebUI keep loosing connection to daemon with the error pop up:

I have no logs in docker nor in the container for this issue and browser just shows error on some rpc URL calls with no HTTP error code, just "net::ERR_CONNECTION_CLOSED"

Expected Behavior

Have a fully fonctional WebUI.

Steps To Reproduce

1. Deploy using this docker compose (adapt traefik labels to your situation)
2. Connect to WebUI URL and go to settings using the hamburger menu icon
3. Click to "Edit Preferences" wait 20-30 seconds: error pop-up should appear

Environment

- OS:Ubuntu 24.04
- How docker service was installed: using the docker-ce packages/repo:

File /etc/apt/sources.list.d/docker.sources :

Enabled: yes
Types: deb
URIs: https://download.docker.com/linux/ubuntu/
Signed-By: /etc/apt/keyrings/docker.asc
Suites: noble
Components: stable

Then "apt install docker-ce"

CPU architecture

x86-64

Docker creation

name: transmission
networks:
  traefik:
    name: traefik
    external: true
services:
  transmission:
    image: lscr.io/linuxserver/transmission:latest
    container_name: transmission
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Etc/UTC
      #- TRANSMISSION_WEB_HOME= #optional
      #- USER= #optional
      #- PASS= #optional
      #- WHITELIST= #optional
      #- PEERPORT= #optional
      #- HOST_WHITELIST= #optional
    volumes:
      - /docker/transmission/config:/config
      - /docker/transmission/downloads:/downloads
      - /docker/transmission/watch:/watch
    ports:
      #- 9091:9091
      - 51413:51413
      - 51413:51413/udp
    restart: unless-stopped
    labels:
      - traefik.enable=true
      - traefik.http.routers.transmission.entrypoints=websecure
      - traefik.http.routers.transmission.rule=Host(`transmission.yourdomain.fr`)
      - traefik.http.routers.transmission.tls=true
      - traefik.http.services.transmission.loadbalancer.server.port=9091
    networks:
      - traefik

Container logs

[migrations] started
[migrations] no migrations found
───────────────────────────────────────

      ██╗     ███████╗██╗ ██████╗
      ██║     ██╔════╝██║██╔═══██╗
      ██║     ███████╗██║██║   ██║
      ██║     ╚════██║██║██║   ██║
      ███████╗███████║██║╚██████╔╝
      ╚══════╝╚══════╝╚═╝ ╚═════╝

   Brought to you by linuxserver.io
───────────────────────────────────────

To support LSIO projects visit:
https://www.linuxserver.io/donate/

───────────────────────────────────────
GID/UID
───────────────────────────────────────

User UID:    1000
User GID:    1000
───────────────────────────────────────
Linuxserver.io version: 4.0.6-r4-ls308
Build-date: 2025-08-26T10:42:59+00:00
───────────────────────────────────────

[custom-init] No custom files found, skipping...
Connection to localhost (127.0.0.1) 9091 port [tcp/*] succeeded!
[ls.io-init] done.

[github-actions]

Thanks for opening your first issue here! Be sure to follow the relevant issue templates, or risk having this issue marked as invalid.

[j0nnymoe]

Do you get the same issue when accessing the container directly via IP:port?

[RastaTaz]

Hi @j0nnymoe ,

Thanks for your quick answer.

I uncommented port 9091 exposure in compose file then restarted, and indeed, the error did not show up.

Must be something with traefik reverse proxy: I should have tried this before raising the bug...
Although this is weird as I have used many containers having WebUIs and never had such an issue.

I also noted that there are way less rpc calls made by the browser using the "dev" plugin (F12 key) when using direct connection...

Thanks again for this suggestion: I'll have a deeper look into my setup.
=> Closing issue as it looks irrelevant to work done by LSIO for "dockerizing" transmission !