It sounds like the service you are calling is not allowing access from your TEST environment. Do you control this service? Can you ask for the Mendix Cloud IP addresses to be whitelisted?
You can find the IP addresses for the Mendix Cloud here. https://docs.mendix.com/developerportal/deploy/mendix-ip-addresses/
Are you using a certificate that expired?
This morning , we reached out to our backend team to check the IP whitelisting thing.
will post the resolution if the issue get resolved.
@Tim van Steenbergen :- We are not using any certificate.
You get “Connection refused” when there’s nothing listening on the host + port combination. In your case it’s possibly you’re not connecting to the right endpoint.
If you get “Connection timed out”, your endpoint is probably correct but there’s a firewall blocking your request/connection.