Servers

In the BakedModel class in SeparatePerspectiveModel, I changed func_230044_c_()/isSideLit() to return always false. That fixed the lighting issue with the GUI icon, but I cannot tell if it had any effect on the 3D model or not. It doesn't seem to have.

I'm very sorry this was entirely user error and something else on my network was causing me to think that the server was not starting but actually it was running and waiting for client connections but clients weren't seeing it.   I'll close this issue and again sorry for the confusion.

User was banned for piracy. Buy the game.

LazyOptional is just that: An optional value that is computed lazily.   No, you need to create a combined IItemHandler by using CombinedInvWrapper. This should not happen inside getCapability, you should create this handler and the LazyOptional once (in your class' constructor) and then just return the value in getCapability.