...

Unfortunately, I believe there is a mistake in the Confluence instructions... so after posting my questions here are my notes to figure this all out.

...

...

...

ProxyRequests Off

Analysis 1

I believe I've found the error. It probably has to do with the search engine. On the test server's application server - with more memory and updated OS and newer Java - making this batch.js request results in a response. However, on the restricted environment it does not,

...

04-Aug-2019 21:50:06.328 INFO [Catalina-utility-2] org.springframework.web.context.support.AnnotationConfigWebApplicationContext.loadBeanDefinitions Registering annotated classes: [class com.atlassian.synchrony.proxy.websocket.WebSocketConfig,class com.atlassian.synchrony.proxy.web.SynchronyWebMvcConfig]
2019-08-04 21:50:06,648 INFO [Catalina-utility-1] [com.atlassian.confluence.lifecycle] contextInitialized Starting Confluence 6.15.7 [build 8100 based on commit hash e6b42acaec191a9bce4ab234dae0b1b08af15496] - synchrony version 2.1.0-release-confluence_6.15-32f7299a
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation

Analysis 2

Now with matching Java version at least, but not 64-bit.

...

Ok same Java version including 64-bit...

Solution!

And that was it!

Make sure to adjust Confluence's context path through the admin console Server Base URL, in my case to www.breakitdown/wiki Here is my current working files,

...