Its not your addons or your wtf folder or any of that shit, trust me, don't delete all that crap and make yourself redo all of your preferences.

In my case the disconnect is very easy to produce. If the lead char stops and follower catches up, the follower disconnects a few seconds later. It does not matter what the leader is doing.

Before 2.1 came out I had the same issue as one of the people above, disconnecting on boats, dunno what that one was all about.

Some people are saying its when you interact with objects or npc's or other things like that. It's not the interaction, its simply that the lead char is no longer moving.

Don't delete all your files, they are not the problem. This is a server side / game code / communication issue. Trust me, I have deleted all mine three times, done a full reinstall twice, and installed all new network hardware. Hasn't changed a thing.