I am trying to install the Android SDK and I get the following error in the SDK Manager Logs -
Failed to fetch URL https://dl-ssl.google.com/android/repository/addons_list-1.xml, reason: peer not authenticated
Fetched Add-ons List successfully
Fetching URL: https://dl-ssl.google.com/android/repository/repository-5.xml
Failed to fetch URL https://dl-ssl.google.com/android/repository/repository-5.xml, reason: peer not authenticated
Done loading packages.
As a workaround, I enabled the "Force https://... sources to be fetched using http://..." setting in the SDK Manager Tools > Options menu.
If you use Android Studio instead of the standalone SDK Manager, Choose "SDK Update Sites" in the "Android SDK" settings and click the checkbox in the lower part of the screen.
That seems to help. I suspect it is a server side problem, but I'm not sure about that.
Edit: Please note that using http instead of https is not really the best idea! In the worst case, a man-in-the-middle attack could inject malicious code into your Android SDK libraries that ends up in your APK. That's why it's called a workaround :)