(Posting this in both major threads about this)
We are still looking into this. It's not happening in a controlled environment, so we are just trying to get a good look at it in the wild. We have some theories and have added some instrumentation to a custom build. If you see WotC_ChrisClay, hope he disconnects. He's playing with the instrumented build because he has experienced a few disconnects over the past couple days.
Thanks for the reports and the feedback. We'll get this sorted out as soon as we can.
P.S. Only we devs know if any unrelated "instrumentation" went into Chris's build...