WordPress in Docker Spits 502 Error after Nginx - wordpress

Question

Trying to dockerise all of my WordPress instances as I now have multiple sites on the same server, and want transfers to go smoothly etc!
I'm running a WordPress and MariaDB instance in Docker on an Ubuntu Server VM inside VirtualBox on a Windows 10 machine. Then installed on the bare Ubuntu Server VM (not a Docker container), is an instance of Nginx. I want my Nginx instance to forward requests from "https://test.domain.com/", to http://127.0.0.1:8181/ (the Wordpress Docker instance).
I can access the install page for the Wordpress instance via 192.168.0.30:8181, so the webserver is running, however test.domain.com gives a 502 error. I'm thinking I need to trust the proxy from within Wordpress? Unsure of how to do that though.
No online article seems to be able to help 😔
Thanks in advance!
docker-compose.yml:
services:
wordpress:
image: wordpress
links:
- mariadb:mysql
environment:
- WORDPRESS_DB_PASSWORD=REDACTED
- WORDPRESS_DB_USER=REDACTED
ports:
- "192.168.0.30:8181:80"
volumes:
- ./html:/var/www/html
mariadb:
image: mariadb
environment:
- MYSQL_ROOT_PASSWORD=REDACTED
- MYSQL_DATABASE=wordpress
volumes:
- ./database:/var/lib/mysql
Nginx Config:
server {
listen 8080;
server_name test.REDACTED.com;
return 301 https://$host$request_uri;
}
server {
listen 443 ssl http2;
server_name test.REDACTED.com;
location / {
proxy_pass http://127.0.0.1:8181;
proxy_set_header Host $host;
proxy_http_version 1.1;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;
}
# SSL parameters
ssl_certificate /etc/ssl/www.REDACTED.com.crt;
ssl_certificate_key /etc/ssl/www.REDACTED.com.key;
# log files
access_log /var/log/nginx/test.REDACTED.com.access.log;
error_log /var/log/nginx/test.REDACTED.com.error.log;
}