LobbyMenu.cs

using UnityEngine;
using Bolt;

public class LobbyMenu : GlobalEventListener
{
    [SerializeField] string _gameplayScene;
    [SerializeField] ushort _port = 27000;
    [SerializeField] ushort _broadcastPort = 27001;

    bool _bClientLANInit;
    bool _bLANConnect;

    void OnGUI()
    {
        GUILayout.BeginArea(new Rect(10, 10, Screen.width - 20, Screen.height - 20));

        if (GUILayout.Button("Start Server", GUILayout.ExpandWidth(true), GUILayout.ExpandHeight(true)))
        {
            BoltLauncher.StartServer(UdpKit.UdpEndPoint.Parse("127.0.0.1:" + _port));
        }

        if (GUILayout.Button("Connect Localhost",  GUILayout.ExpandWidth(true), GUILayout.ExpandHeight(true)))
        {
            _bLANConnect = false;
            BoltLauncher.StartClient();
        }

        if (GUILayout.Button("Connect LAN", GUILayout.ExpandWidth(true), GUILayout.ExpandHeight(true)))
        {
            _bLANConnect = true;
            BoltLauncher.StartClient();
        }

        GUILayout.EndArea();
    }

    public override void BoltStartDone()
    {
        if(BoltNetwork.isServer)
        {
            BoltNetwork.LoadScene(_gameplayScene);
            BoltNetwork.EnableLanBroadcast(_broadcastPort);
        }
        else 
        {
            if (_bLANConnect)
            {
                BoltNetwork.EnableLanBroadcast(_broadcastPort);
                _bClientLANInit = true;
                BoltLog.Info("Searching for server...");
            } else {
                BoltNetwork.Connect(UdpKit.UdpEndPoint.Parse("127.0.0.1:" + _port));
            }
        }
    }

    void Update()
    {
        if (_bClientLANInit && !BoltNetwork.isConnected)
        {
            foreach (var session in BoltNetwork.SessionList)
            {
                BoltNetwork.Connect(session.Value.LanEndPoint);
                break;
            }
        }
    }
}