Mendix webservices: cannot find the declaration of element 'S:Body'

While working on an integration issue between 2 Mendix Apps, we kept running into an issue where a locally developed and tested integration worked fine, but after deploying it on the Test environment, errors kept occurring. Debugging led to the specific error " cannot find the declaration of element 'S:Body' " and in the java stack trace the mention of the Xerces libray, which handles Java webservice integration. Most likely (pending further investigation...) this means it's a server environment configuration issue. It seems to be that Mendix is not able to interpret (deserialization?) the incoming request. Can it be the the SOAP library is not available?

There are 2 options we are exploring:
- newer JRE version to be installed on the server
- settings of the VM need to be updated as the server is running On Premise.
This is our current approach for further researching a solution for this error:

There is an issue since Java 7, causing timeouts when using Web Services with a certain amount of data. You can circumvent this issue by adding the VM params "-Djava.net.preferIPv4Stack=true". The Mendix Business Modeler will do this for you but if you are running Mendix on premise on a Windows server you will need to do this yourself.

As found in the Mendix System Requirements.