WebRequest (example) - HTTPWebRequest - 403 message

I’m using WebRequest (example) to test some HTTPWebRequest GET statements. I composed/tested a number of GET requests using Insomnia. They work, and return data, in Insomnia. A demo request (from the API documentation), which uses no parameters, successfully retrieves a static HTML page as it is supposed to. The other GETs, which include parameters, return error “403 - access denied.” Any thoughts on this? I’m running CW 11, build 13630. Windows 10 pro.

PS - “Validate certificates” setting in Insomnia is turned off. Might that be the problem? Is it possible to do that in CW as well? What are the downsides?