Realm returns 'Server Closed' while playing.

When I'm playing on my friend's realm, the server will randomly close for no reason. I'll be playing in the realm with no other players, and the server will semi-randomly return a 'Server Closed'. When you reconnect after a while of the server being down, it will normally have rolled back, suggesting the Realm has crashed somehow. It seems to happen when I'm strip mining, and can be recreated by strip mining in one particular direction for an extended amount of time.