I can receive and update Greenhouse fine using the address: https://greenhouse.lotus.com Is this the address you are using?
The best way to determine you are using the correct address is to browse to your profile page on the Connections server, then copy everything before /profiles/ in the URL.
becomes https://greenhouse.lotus.com in WildFire
Sometimes they are not always so easy, like Developerworks
becomes https://www.ibm.com/developerworks/mydeveloperworks in WildFire.
Could you please check you can access the server using your browser and copy the correct address. Also, if you can retreive but not post, make sure you are using https instead of http.
Let me know how you go.