I'm having a problem calling the API's method `CompleteSale` via eBay\_Service .NET SDK (v967) since 2 weeks (02/10).   

When the ERP tries to sends some updated information about one order, it receives this Exception: 

> 
> the underlying connection was closed an unexpected error occurred on a send
> 
> 
> 

so I haven't got a response from the API.   

There are more than one strange things:

* there are some batch in background, using the same .dll, and they
work fine;
* after rebooting the server the first call to "CompleteSale" works fine;
* after registering again the .dll via the "regsrv" command, it worked 
fine for one day;
* all operators that uses the ERP are connected to the server via
remote desktop and all of they notice the problem. Instead, if i
connect from my company's office, all works fine;
* I've tried to increase the timeout to 360 sec (from 60 sec) and nothing changed.

The ERP is developed in progress (OpenGL) ~~, so I can't fix with setting "KeepAlive" to "false", setting the certificate explicitly (Tsl1.1 | Tsl1.2) or making other interventions on .net side.~~ I was wrong, it can be done from the source code of the SDK.