Install Gramps on an YUNOhost server - reverse proxy issue

Hi !
I try to install Gramps Web on my server, an old computer on YunoHost (stable).
I deployed gramps with docker like explain on this page
Gramps Web work properly on local network : I made it work on 5555 port, but when I try to use the reverse proxy app or the redirect app (with reverse proxy option) to redirect them to the right port, I can’t get access to the app.

I just got the right information on the browser tab (favicon and Title) but nothing on the tab.

Thank you for your help

That’s really hard to say. I suggest setting up some simple hello world web server image (instead of Gramps Web) with reverse proxy and get that to work first.

It appears that the index.html is served : the page code source is the one of index.html.
But no other information is on the page, I am not redirected to login page.

Here one screenshot : that might help to get more precision on the problem