In your scenario, the connection string for the Domain Model is taken from the web.config file of the WCF Service project. When you initialize the entities in the service, OpenAccess will always refer to the web project configuration rather than the model app.config.
This means that if you change the connection string only in the web.config file, the WCF service will work correctly.
There are two things to bare in mind. First, when you change the connection string, it has to be pointing to a database with the same schema. Second, in case another project refers to the Domain Model project, it will use its own configuration (app.config or web.config). Also, if the model project can be used by itself (console application, windows application, etc.), the connection string will be loaded from the app.config.
For more information, you can refer to this documentation article
If you have any other issues, please feel free to contact us.
All the best,
the Telerik team
Telerik OpenAccess ORM Meets ASP.NET Web API. Read more.