multi TargetFrameworks project (.NETStandard with .NET Framework4.0 and 4.5) for interacting with SOAP Service?

I can't find a clear answer about my issue after I've been doing some research for hours .

I basically need to make Nuget Project (library) that interacts with the SOAP service. And for mandatory reasons the nuget must be in multiTargetFrameworks.

The problem that :

• for .net Framework 4.0 the way to interact with the service is : right clicking then "Add Service Reference" > "Advanced" > Add Web Reference.
• for .netStandard the way to interact with the service is :right clicking Dependencies and selecting "Add connected service" then choosing "Windows WCF Web Service Reference Provider".

And when the project is multiFrameworks "References" does not exist and if I just use "Add connected service" for both of Frameworks and I connect my service; there is compatibility problems with System.ServiceModel with .net framework 4.0

PS: I have to keep this version of frameworks, other than that I would be open to any suggestions.