I am trying to install the Android SDK and I get the following error in the SDK Manager Logs -
Fetching https://dl-ssl.google.com/android/repository/addons_
It is very likely that you are getting this when you are within a corporate network and your corporate is using some sort of Browser proxy.
If that is the case and you are using VPN software to get on the corporate network, then disconnect from the VPN to allow your machine to be on the Internet "directly".