When UpdateSunDirection is called, the skylight intensity increases considerably(about x100) for the client but not the server. In a dedicated server, all clients have increased intensity too.
I think this is a bug because this could be fixed by decreasing the scale of the SkySphere static mesh to no more than 30(default 400), or at least it starts getting brighter on the client side when it reaches 30.
It can also be fixed by not calling the Material function SetVectorParameterValue in the UpdateSunDirection function.
ColorsDeterminedBySunPosition may make the problem less apparent but it still persist.
And offcourse, removing the skylight fixes it.
I guess this could be a material bug.
Server view. Increasing skylight intensity to 100 will show what the client sees
Client view
Here’s a project
[link text][3]