The CMIS discovery document returns absolute template URLs that have to be used to navigate the repository and retrieve node information.
By default the hostname of the server is returned in the URLs, if the server is behind a proxy the hostname needs to be configured to return the publicly accessible hostname.
For the webscript based CMIS implementation this was possible by placing a "spring-webscripts-config-custom.xml" config file in <tomcat>/shared/classes/META-INF
It appears the same thing is not possible for the /cmisatom entry point as it uses a separate servlet and not the webscript engine.
A solution has been implemented  for Cloud as this entry point is used there and obviously the Cloud sits behind a proxy or two!
This solution needs to be merged to the 4.x codeline ASAP as currently no one with this configuration can use the Android App against a 4.x server!
 The following config can be used on Cloud:
- The servlet path, context path and server can all be selectively overridden
- if true, the servlet path of OpenCMIS generated urls will be set to "opencmis.servletpath.value", otherwise it will be taken from the request url