Cardinal-Components-Item will not let clients join a dedicated server. Attempting to do so results in a malformed input error. It seems likely that this stems from MixinPacketByteBuffer, although I can't pinpoint what it's doing that causes this (besides reading a bad packet).

To replicate, create a blank project and include cardinal-components-item, then run a client and server with online-mode turned off. Connecting to the server will fail, resulting in this:

Until then, mods using Cardinal-Components-Item seemingly won't work in multiplayer.

Trying this on a dedicated server outside of a dev environment is even less specific, all that gets spit out on the server it:

[00:45:57] [Server thread/INFO]: X joined the game
[00:45:57] [Netty Server IO #1/ERROR]: java.lang.NullPointerException
[00:45:57] [Server thread/INFO]: X lost connection: Internal Exception: io.netty.handler.codec.EncoderException: java.lang.NullPointerException
[00:45:57] [Server thread/INFO]: X left the game
[00:46:17] [Server thread/INFO]: Stopping the server

However, it does work when connecting two clients via an integrated LAN server (at least in a dev environment)

It turns out that there's no clear way to reproduce this so far, but here's a gist containing a log:

clientside crash log

This is with CCA 2.4.0-nightly.1.16-pre2