s&box Network Events Reference

using Sandbox;

// Implement INetworkListener on a Component placed in the scene to react to lobby events.
public sealed class GameNetworkManager : Component, Component.INetworkListener
{
    [Property] public GameObject PlayerPrefab { get; set; }
    [Property] public GameObject SpawnPoint { get; set; }

    /// <summary>The client just opened a connection — handshake hasn't finished.</summary>
    public void OnConnected( Connection connection )
    {
        Log.Info( $"{connection.DisplayName} connected — handshaking..." );
    }

    /// <summary>The client is fully in. Spawn their player here.</summary>
    public void OnActive( Connection connection )
    {
        var player = PlayerPrefab.Clone( SpawnPoint.Transform.World );
        player.NetworkSpawn( connection );
    }

    /// <summary>The client left for any reason. Clean up.</summary>
    public void OnDisconnected( Connection connection )
    {
        Log.Info( $"{connection.DisplayName} left." );
    }
}

// Implement INetworkSpawn on a Component to react to its own object being networked.
public sealed class FlashOnSpawn : Component, Component.INetworkSpawn
{
    public void OnNetworkSpawn()
    {
        Log.Info( $"{GameObject.Name} just appeared on the network." );
    }
}