One possibility is that Google sees too many versions of the index, e.g. uk.testmy.net, dallas.testmy.net, etc. and only lists a few variants. I remember this being a pain in the past in the Joomla 1.x days where it would show the same page under various URLs and Google usually ended indexing obscure URL variations of some pages.
Both Bing and DuckDuckGo have the main test.my homepage URL indexed, so it doesn't seem to be something preventing crawlers from indexing it.
One thing I suggest is adding a Canonical meta header tag to the home page to specify "http://testmy.net" as the preferred URL, as explained here.