I am getting an error when trying to connect cloud studio 2005 to my test C4C environment version 2005.01.0017. I get the "System cannot be reached" error.

The user account I'm using has PDI_PARTNER_DEVELOPMENT access rights assigned.
The solutions proposed here https://answers.sap.com/questions/12709757/sap-application-studio-1905-login-errorthe-system-.html DID NOT help. I couldn't find the registry keys that were mentioned in that answer. I tried renaming the project folder, it generated a new one but I still got the same error.
When the version was 2002, I had no problems connecting and it was the same machine on the same network. This issue arises after upgrading to 2005. I tried installing it on another machine on the same network, same error. Any other ideas on how to resolve this issue?