Help proxying with plain Nginx

[blackmyre]

I'm trying to set up reverse proxying for Adventurelog using plain native Nginx - not installed in Docker, and not Nginx Proxy Manager, so most of the hits I've found aren't quite right. After far too much time going around in circles it's high time I accepted that I don't really know what I'm doing and begged for help in here (please let me know if there's somewhere more appropriate). Apologies for a lengthy post, I tried to keep it as brief as I could while including all the relevant information.

My Nginx is installed directly on a Linux OS host (actually an LXC, just in case that matters). I have a wildcard SSL certificate (*.mydomain.tld) installed there. I also have a handful of other Dockerised web applications (mostly Flask-based) running on that host and I have them all proxied through Nginx. I access them as e.g. https://myapp1.mydomain.tld, which uses proxy_pass to http://myapp1.mydomain.tld:port, with myapp1.mydomain.tld being set in my DNS server as an alias of the host. It all works just fine.

I have a Docker install of Adventurelog on that same host. It works correctly when I point a browser at its IP:8015. I naively thought I would be able to basically clone one of my existing configurations with appropriate minor changes so I could access it as https://adventurelog.mydomain.tld, but I think I'm failing with its frontend/backend arrangement. Pointing a browser at https://adventurelog.mydomain.tld works, but login fails with a 403. I suspect CSRF restrictions are at least part of my problems. Can anyone suggest how I should configure things given the following simplified parameters:

Hostname nginx, with DNS entry pointing nginx.mydomain.tld at its IP.
Standard Adventurelog Docker installation on that host: frontend port 8015, backend port 8016.
DNS CNAME entry making adventurelog.mydomain.tld an alias of nginx.mydomain.tld

My current (failing) effort is outlined below. If I've missed any relevant details please just ask.

Thanks!

==============================================

nginx
-----
# Proxying for AdventureLog Docker installation
# frontend proxy
server {
    listen 443 ssl;
    server_name adventurelog.mydomain.tld;
    location / {
        proxy_set_header Host $http_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        proxy_pass http://localhost:8015;
    }
}
# backend proxy
server {
    listen 443 ssl;
    server_name adventurelogmedia.mydomain.tld;
    location / {
        proxy_set_header Host $http_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        proxy_pass http://localhost:8016;
    }
}
==============
.env
----
PUBLIC_SERVER_URL=https://adventurelogmedia.mydomain.tld
ORIGIN=https://adventurelog.mydomain.tld
FRONTEND_PORT=8015
PUBLIC_URL=https://adventurelogmedia.mydomain.tld
CSRF_TRUSTED_ORIGINS=https://adventurelog.mydomain.tld,http://adventurelog.mydomain.tld,https://adventurelogmedia.mydomain.tld
FRONTEND_URL=https://adventurelog.mydomain.tld
BACKEND_PORT=8016
====

[blackmyre]

Cancel that question, it is in fact behaving pretty much as expected but I was doing something stupid. Sorry about the needless post.

[madindehead]

Not a needless post - came here looking to see how to proxy using regular nginx and this has helped me understand I need the two domains.