Getting Cannot Send the test request error

Hi ,
I am new to Katalon Studio(API testing) . While sending a GET request got below error

From Katalon studio Object repository got the below error.
image Unexpected end of file from server
at com.kms.katalon.core.webservice.common.RestfulClient.response(
at com.kms.katalon.core.webservice.common.RestfulClient.sendRequest(
at com.kms.katalon.core.webservice.common.RestfulClient.send(
at com.kms.katalon.controller.WebServiceController.sendRequest(
at org.eclipse.jface.operation.ModalContext$

Please not the server is not responding , from postman got this error " Could not get any response There was an error connecting to []"

Kindly suggest.