Calling a managed dll from Test Project

I have been facing a weird problem, where i write a code that wraps the calls to a dll of 3rd party system , the code itself is working correctly -it communicates with another SW , so it has to establish a connection within a configured time - when run from a console application.

When tried to run the same code from a Testing Project (a class library project that has nunit nuget pkg) it gives a different behavior(mainly time out after less time). i know that this is not a unit test for sure, but this is not the point , the main issue is a code that is run with a different behavior in the Testing Project i have tried Ms Test and Nunit.

based on this post(Is this DLL managed or unmanaged?) this dll is managed. I do not use any dll imports syntax neither in the source code nor in the testing code. Any suggestions are much appreciated.