I'm not 100% sure it's because of Ars, but whenever I'm by the server's spawn or my farm, Java crashes. Not Minecraft, the Java runtime enviroment. In the log, i see this right before the stuff about ...

Hi there, on my heavily modded (~300 mods) server the iron farm item will crash my game when in my hand. Making the usage of the item impossible. However the other player doesn't have the same issue ...