When Confluence is deployed on servers which use a outbound HTTP proxy to communicate externally, the proxy information needs to be configured in the Java Virtual Machine (JVM) properties on the application startup. This information will be used by the confluence macros at run time to communicate with external URLs. If the proxy information is missing or is incorrect, the macros would timeout trying to connect to external URLs.
You must be a System administrator to configure this capability.
A number of our macros provide the capability to bring data in from external sources via a URL. Here are some that would benefit from this configuration.
Configuring Outbound Proxy - this article is written for JIRA, but the same configuration applies to Confluence or similar applications.