Using HTTPS POST in Groovy

I am trying to write the Groovy Custom SR of an E1 orchestration to take a passed in data set and transfer it to a remote server using HTTPS POST. I have cobbled together what I think I need and built the request including a bearer token, but when I try to run the script I always get the error:

"java.net.ConnectException: Tried all: 2 addresses, but could not connect over HTTPS to server: <server_name> port: 443"

We installed TLS 1.2 on the server and get the same result and have tried using a proxy server with certificates installed, but get the same result.