I have a similar issue. I'm testing out wyBuild and was first testing out downloading from localhost. Now, I've moved the updates to a web server, that's accessible to the internet. On one of my test clients with no access to the localhost I get the error: "Error downloading http://localhost... Cannot connect to the remote server."
This is the download address that used to be configured in wyBuild and a setup kit containing the client.wyc file with this setting was installed on the test computer and the automatic download was attempted. However, now a new setup kit, including a new client.wyc file with the new download address has been installed. I assume the download address is included in the client.wyc file? If this is the case, it seems like the download address is also cached somewhere in the computer from the old version. Would this be correct and how would I remove this cached address?