Minecraft snapshots cannot be tested in multiplayer because the new things are not available on a snapshot server, since you need the datapack to test all new things and the datapack is not downloaded to the snapshot server when you start it for the first time
[media]
MC-259588
Snapshot items not available on snapshot server
Resolved
Invalid
0
Turn on the experimental data pack before generating the world, via the server.properties file (the packs still exist within the server jar).