AX 2012 Multiple aos webservice connection issue

We have 4 AOSes (3 + 1 batch aos) based on one database.

There are 3 custom components: ax Class, that calls external c# dll, C# DLL, that calls AOS webservice and AOS webservice, that allows to create new records in ax.
1.AOS -> 2.DLL -> 3.AOS webservice

The logic is to call from ax functionality, get external information, process it and then store into ax.
Since all AOSes based on one database, we want to have a deployed webservice only on batch aos.
So when we call a DLL, we pass to it batch aos webservice endpoint address.
If we make call from batch aos, everything works good by a standard scenario defined before. So it looks like this: BATCHAOS -> DLL -> BATCHAOS
But when we try to make a call from another aos ( AOS1 -> DLL -> BATCHAOS), we get an exception "a call to sspi failed see inner exception", that appears in DLL on ServiceNameClient object, when .create() method is called.
We checked webservice endpoint address and ports, so in dll app.config endpoint address is correct.

The question is: What should we do to be available to call webservice on one from another?
Bellow you can see screenshots of batch aos webservice, deployed dll app config and code block, where communication object is created. Screenshots are from batchaos only since all of aoses uses the same dll. In app config endpoint address is got from webservice URI addres and AOS_SERVICE_HOST is replaced with aosName+URI port