The links you provided have nothing to do with the problem that my friend is facing. Every 3-4 minutes, my friend get disconnected from the server and gets the exact same error, it saying "Lost connection to the server"
We tried it on a test world and he could stay there for more than 15 minutes. We don't know if it could be a coincidence. Right now, am I facing another problem, and it is the upload limit that does not allow you to upload worlds that are over 200mb. I can't find anyone else that has the exact same error (talking about the connection) which makes it harder for me to workaround this. For now, I will play on a hamachi singleplayer world instead. Hope that this may get resolved, or my world getting uploaded.
(Edit) Looking back at the previous post that the Engineer made, I've just noticed that you said "Try to create a second account" while I just downloaded and removed my world and created a second test one, I don't know if this makes a difference, and I hope not. My bad!