Try replacing the endpoint address="https://abc/v2/webservices.asmx" with a fixed ip address if possible, e.g.
Also you might need to add a port to the ip address.
Also make sure your firewall is not blocking the communication.
Also make sure you don't have settings in your project that interfere with app.config, try to remove the lines:
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />