May be related to #100

With this mod, vanilla clients aren't able to join. They need to install Cardinal Components API or this mod. The following message is displayed:

this server requires cardinal components api (unhandled packet: cardinal-components:entity_sync)

This seems to be related to this issue: Mod now required on client-side. This thread refers to the migration guide for upgrading from CCA 5.X to 6.0, which can be found here