And what server is 10.0.55.2?
I have a guide here that shows how to set up a reverse proxy. It’s written for proxying a Docker setup, but the basic concept is the same.
https://help.nextcloud.com/t/howto-ubuntu-docker-nextcloud-talk-collabora/76430
I did a reverse proxy for SOGo once and don’t recall having to enable so many mods. It would help to see your Apache site configs.