Reachability test to certain server doesn't work

[dailycafi]

Even in example, if you try to test the connection to github.com(or any other host). The first time it works, but after you test it, you disconnect your network, then reconnect it, the status for connect to the server will always be unreachable.

[hyling]

This works for me on iOS. I tested reachability before and after I toggled airplane mode and it reports the correct status both times. How did you test?