SAP NetWeaver is an application and Integration Platform. It is open for SAP and Non-SAP applications. It is used by organizations to improve productivity by making all the resources in an enterprise work collectively. Various corporate sectors and Organizations will have to take a decision for some common platform; Microsoft .NET, IBM Websphere or SAP NetWeaver. Irrespective of the choice that they make, SAP NetWeaver is the one that integrates with all the three technologies.
When you run the application from MII navigation menu, perform a network trace to see which call is failing. Based on that further analysis can be done. Let me know if you can share your screen using AnyDesk software to enable me debug this further.