Calling Rest API

Failure to call a function on a payment provider API

I have created this three lines of code:

HttpWebRequest := HttpWebRequest.Create('https://sandbox.spryngpayments.com/v1/api_key');
HttpWebRequest.Method := 'GET';
HttpWebRequest.Headers.Add('X-APIKEY','DUMMYAPIKEY');
HttpWebResponse := HttpWebRequest.GetResponse;

Last Line raises error message:
A call to System.Net.HttpWebReqiuest.GetResponse failed with this message: An Existing connection was forcibly closed by the remote host.

Also when I use a valid APIKEY

When I try with postmand, noproblem whatsoever.