Hi @dynamicat,
I managed to reproduce the initial error (504 Gateway Timeout) and I found a fix for this.
The error comes from your networks, you created 2 networks and the authelia container is assigned to both of them. Traefik, while forwarding, doesn't know which network to use. So you have to specify it in your docker provider configuration:
- --providers.docker.network=t2_proxy
And as I said, other configurations seem good to me. Could you try to fix?
Let me know if you need more help 