Try on local it works perfectly fine but starting server with mod produce err as below:

caused by: java.lang.NoClassDefFoundError: net/minecraft/class_310
at mc.craig.software.angels.network.WANetworkManager.make(WANetworkManager.java) ~[fabric-weeping_angels-mc1.21-v1.0.0.jar:?]
at mc.craig.software.angels.network.WANetworkManager.(WANetworkManager.java:24) ~[fabric-weeping_angels-mc1.21-v1.0.0.jar:?]
at mc.craig.software.angels.WeepingAngels.init(WeepingAngels.java:45) ~[fabric-weeping_angels-mc1.21-v1.0.0.jar:?]
at mc.craig.software.angels.fabric.WeepingAngelsFabric.onInitialize(WeepingAngelsFabric.java:54) ~[fabric-weeping_angels-mc1.21-v1.0.0.jar:?]
at net.fabricmc.loader.impl.FabricLoaderImpl.invokeEntrypoints(FabricLoaderImpl.java:399) ~[fabric-loader-0.16.0.jar:?]
... 7 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.class_310
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641) ~[?:?]
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526) ~[?:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:226) ~[fabric-loader-0.16.0.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119) ~[fabric-loader-0.16.0.jar:?]
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526) ~[?:?]
at mc.craig.software.angels.network.WANetworkManager.make(WANetworkManager.java) ~[fabric-weeping_angels-mc1.21-v1.0.0.jar:?]
at mc.craig.software.angels.network.WANetworkManager.(WANetworkManager.java:24) ~[fabric-weeping_angels-mc1.21-v1.0.0.jar:?]
at mc.craig.software.angels.WeepingAngels.init(WeepingAngels.java:45) ~[fabric-weeping_angels-mc1.21-v1.0.0.jar:?]
at mc.craig.software.angels.fabric.WeepingAngelsFabric.onInitialize(WeepingAngelsFabric.java:54) ~[fabric-weeping_angels-mc1.21-v1.0.0.jar:?]
at net.fabricmc.loader.impl.FabricLoaderImpl.invokeEntrypoints(FabricLoaderImpl.java:399)

@Jeryn99 btw.. great work with the mod! ;)

Hello. Please ensure your issue is not already reported via the search bar before creating a new issue.

Duplicate of #366

My bad I thought it was different issue, thanks.

Hello. Please ensure your issue is not already reported via the search bar before creating a new issue.

Duplicate of #366