Static Mesh location changes in Multiplayer

Hi,
I have this problem in both 4.7 and 4.8. I have a multiplayer (2 person) setup running with both windows open on the same machine. There is a concrete barrier. I have tried this as just an actor placed in the scene and also as a blueprint with the replication components all selected. The problem is if a player collides with the mesh its location differs on each screen. In the case of the client screen it is as if the object has no weight whatsoever and flies out of the screen.

I have attached a screenshot from both the server and the client. Notice the location of the characters in the screen but the difference in the location of the concrete barrier. Can anyone please tell me what I am doing wrong ???

Thanks,
Ben

49234-clientpic.jpg