Can't connect to/access realms despite having multiplayer and clubs enabled.

My friends have a realm set up that I am trying to re-join, however despite having the necessary setting enabled it still says I can't do so. This isn't a child account, it's a personal account that should be able to do this just fine. All the featured servers block my access claiming I'm not logged in or can't be validated. My iPad lets me add realms, join servers and play on my friend's realm just fine. I don't get the problem. I've tried restarting, logging out and changing settings around.