How to use multiple NGINX reverse proxy servers - nginx

Question

NGINX works great as a reverse proxy for my virtual servers to host applications using a single IP address and multiple domain names.
I have one particular VM that runs several node apps that work together as one web application. That server runs its own NGINX reverse proxy to handle everything and works great when exposed to the internet with a unique IP.
Since I want to use my single IP to serve this and the rest of my things, I'd like to configure my primary NGINX server to pass everything off to that server's NGINX instance to handle, which seemed pretty straight forward but isn't working as expected.
On my primary NGINX server (that all traffic is sent to from the firewall) I have configured a site file like this:
server {
listen 80;
listen [::]:80;
server_name example.domain.com *.example.domain.com;
client_max_body_size 1G;
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Real-IP $remote_addr;
location / {
proxy_pass http://10.10.10.10;
}
}
This results in a 502 error. The applications do require web sockets and each have unique subdomains so of which are pointed at directories on that server.
Am I missing some config or thinking about this incorrectly?