Why put nginx in front of your app server? — by blueben on Server Fault

A plain-English explanation: a load balancer spreads requests across several servers, while a reverse proxy is a broader tool that can load-balance and also cache, terminate SSL, compress and filter traffic. Often one product does both jobs.

With one public IP and a domain, run a single nginx reverse proxy that sends device1.example.com, device2.example.com and so on to different internal servers by name. Only that one proxy needs ports forwarded. Anything exposed this way should be secured (HTTPS, authentication) or kept behind a VPN instead.

Proxies rewrite headers such as redirects, but not the links inside the page, so an app that uses absolute paths (/css/style.css) breaks under /subfolder/. The answer lists the real options: make the app use relative paths, deploy it under the same sub-folder internally, or rewrite page content with a filter module as a last resort.