Has Apple blocked us?

I was interested to see your response to John R Gordon’s problem ( MF282) with what had been his daughter’s MacBook. My husband tried to use Internet Recovery on his MacBook Air, to take it back from Yosemite to its original Mountain Lion installation. He was unable to do so and even contacted our ISP, Zen Internet, who could only conclude that Apple must have ‘blocked’ the UK from this facility. Could you please explain how Internet Recovery should work? Susan Platter Macs have two ways to reinstall the operating system. Recovery mode (restart with ç+r held down) will restore from the recovery partition on their internal storage, which will contain the most recent version of OS X installed on your Mac. The other way is Internet Recovery, which downloads the original OS version that shipped with your Mac. To use this, restart with ç+å+r.

Now, if that doesn’t work, it certainly isn’t because Apple is blocking the service in the UK – that would make no sense at all. But your ISP or the firewall on your router may be doing so. Internet Recovery needs to be able to contact two specific server names. You can check this is working from Network Utility (use Spotlight to search for it, because it’s not in the Applications folder). Enter osrecovery.apple.com as the address and get it to scan ports 80 and 443. Network Utility only lets you scan contiguous ranges of port numbers, so you will have to run one scan from 80 to 80, and another from 443 to 443. If you try scanning from 80 to 443 in one go, it will take ages while it waits for all the invalid ports to time out. If the ports open correctly, you will see a message saying “Open TCP Port: 80 http” – or “https”, in the case of port 443. If the port can’t be opened, there will be a long pause and then it will simply say “Port Scan has completed”. Do the same thing for oscdn. apple.com. If either port on either server does not respond, then a firewall or proxy server somewhere in your internet connection is blocking access to the necessary servers, or your DNS server isn’t generating the right internet address for the server names. This sounds complicated, but this test is just to enable you to show your ISP that the problem is its to solve.