So first, is this preventing you from using the sever? (Causes close, etc). If so, then there seems to be something to do with how it is rendering the lighting of blocks. More description is necessary to help out. I suggest edit the original post, and title. Also, I say the same as above; are there any server plugins or mods? Especially anything that changes how things are rendered, e.g overhaul. Try running the server on a fresh install of terraria (move your installation and re-download.) Please document what happens there, and we can isolate where the bug is originating.