For doing that, I followed this old post from Unity Wiki Site. Editor It works fine. UWP -> .Net Scripting Backend I have to exclude my supplied System.ServiceModel.dll from WSA Player, then it works fine. UWP -> IL2CPP Scripting Backend on .Net4.x With the help of System.ServiceModel.dll and an link.xml file, I can get a build from Unity and a successful Compile from VS. But it ends up with this exception: Code (CSharp): NotSupportedException: ..\mscorlib\System.Runtime.Remoting.Proxies\RealProxy.cpp(21) : Unsupported internal call for IL2CPP:RealProxy::InternalGetTransparentProxy - System.Runtime.Remoting is not supported. Standalone -> Mono Scripting Backend on .Net4.x A successful build in Unity, with a help of a link.xml file, it works fine. I tried: On this page and this page and also in this GitHub post Unity says, on IL2CPP backend, stripping on unused assembly engine code is happening and you can make a whitelist by creating a file link.xml and specify which assemblies should be left untouched. It helps me in case of Standalone Mono but I could not figure it out for IL2CPP. Based on this written tutorial about having WCF in Unity, proxy class of the WCF service can be generated with two different Compilers, svcutil or wsdl. The generated .cs class needs System.ServiceModel.dll the second one needs System.Web.Services.dll. Both of work fine in Editor but throws two different exceptions with IL2CPP. I tested ASP.Net in Unity with IL2CPP backend with the help of System.Web.Services.dll, based on this written tutorial, but I received the same error code from WCF generated code from wsdl.exe: I could be able to bypass NullReferenceException: Object reference not set to an instance of an object at System.ServiceModel.MonoInternal.ClientRuntimeChannel..ctor exception with this link.xml file. Conclusion There are two possibilities here, either it can be working with a properly written link.xml file or it is NOT supported on Unity IL2CPP AOT Compiler as of 2018.03.