Duplicacy Web (docker) behind Authelia

I am using the superb Duplicacy GUI docker instance by @saspus. Thanks a lot!

I have all my sites sitting behind Authelia to provide stronger authentication and get prompts on my mobile using Duo integration.

After putting Duplicacy GUI behind the “standard” config to integrate Authelia I am getting a “400 Bad Request” error after successfully completing authentication.

I found people had a similar issue with Home Assistant access behind nginx which needed to understand the trusted proxy IPs, otherwise a 400 Bad Request was thrown.

https://www.reddit.com/r/homeassistant/comments/og1hao/400_bad_request_error_behind_nginx_proxy_manager/

Duplicacy Web behind nginx is working fine, but when I add redirection to my Authelia authentication service this seems to break something.

Is this something Duplicacy Web supports or am I barking up the wrong tree?