WCF Client in .NET 4.5.1: How to enable TLS 1.2 when WebRequest is used?
While not easy to figure out, the needed property is:
This can be used to disable and enable TLS levels in the WCF environment.
Further, you can see what WCF is currently set to using:
With thanks to: How do I disable SSL fallback and use only TLS for outbound connections in .NET? (Poodle mitigation)
You should work with .NET 4.5 or above version and add this line in your code:
System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;