Follow these steps to diagnose and solve your issue:
Firstly, check that you are not having network or firewall connectivity issues by entering the URL in to an up to date browser. Make sure that the URL is correctly formatted. If the URL does not work then you should check your configuration so that you have access to https://api.edq.com/capture.
If you have ruled out connectivity issues then you may be experiencing issues with TLS compatibility. TLS 1.2 and SHA-256 support is required of the client by https://api.edq.com. If your client does not know about, use or support these then you will see problems. In .NET you will get the following exception
WebExceptions - Underlying connection closed. This is a result of .NET 4.5 and below defaulting to use TLS 1.1.To solve this problem in .NET, either recompile in .NET 4.6 or above (which defaults to TLS 1.2) or add the following line to your program:
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12
In order to use our services, you need to ensure that certain IP addresses and address ranges (listed below) are accessible to you (i.e. not blocked by your firewalls).