Can't log in on Android

No need to delete, especially since the original post now has replies, you can delete the post but not replies, so it would look weird.

There is a known issue in the US with T-Mobile and Sprint providers, looks like these providers will default to IPv6 addresses only, which does not work well with Hearthstone. I see you posted your Tech Support question on the EU server, so presumably you are not in the US. However, I could believe that some European providers behave similarly.

So if you have made recent changes (new phone, new provider, new data plan, etc.), it could explain it. You could have a look at the workaround I linked to in that thread, maybe it will help you.