Version: 2018.1
public ushort FragmentSize ;

Description

Defines the fragment size for fragmented messages (for QOS: ReliableFragmented and UnreliableFragmented). Default value = 500.

Under fragmented quality of service modes, the original message is split into fragments (up to 64) of up to FragmentSize bytes each. The fragment size depends on the frequency and size of reliable messages sent. Each reliable message potentially could be re-sent, so you need to choose a fragment size less than the remaining free space in a UDP packet after retransmitted reliable messages are added to the packet. For example, if ConnectionConfig.PacketSize is 1440 bytes, and a reliable message's average size is 200 bytes, it would be wise to set this parameter to 900 – 1000 bytes.

using UnityEngine;
using UnityEngine.Networking;

public class ExampleScript : NetworkBehaviour { void Start() { ConnectionConfig myConfig = new ConnectionConfig(); myConfig.AddChannel(QosType.Unreliable); myConfig.AddChannel(QosType.UnreliableFragmented); myConfig.PacketSize = 1440; myConfig.FragmentSize = 900; } }