I'm having the same problem. I was Server hopping to discover new islands to raise my level cap because I was 49 , Most would just spawn me at the bottom of the ocean or below the ground and after a min i would die and pick a new one. But on one it disconnected when i was falling threw the earth and could not reconnect after that . Here are my possible reasons why.
1) So this is what im guessing is going on , Because areas on the map are different servers when you load from Server A to B your char information is Copied in a way and because you may gain levels and or exp in that server when switching to a new one it needs the information from the previous and because the server i somehow went into was corrupted or down it makes it impossible for new servers ( working servers ) to receive my player data putting me into a limbo . because it won't try and collect player data from any other server than the one i was previously on
2) Anticheat, Soft ban. This is why people can log in for you from elsewhere and you cant , also explains why people report they can log in after 30 - 40 hours
3) Because my char is under the map currently when trying to load in it just messes things up and boots me.