使用MQTTnet（Version=4.3.1.873）库实现多客户端连接多服务端，同时实现断线重连；

如下图所示，开启3个客户端连接3个服务端，当其一个服务端出现异常(服务停止，网络异常无法连接)导致连接断开时，实现每5秒连接一次

MQTT连接服务核心类：业务需求是一个客户端对应的一个MQTT服务，因此按照服务端个数创建对应的客户端连接，实现通过每一个服务端订阅消息，获取数据

using MQTTnet.Client;
using MQTTnet.Diagnostics;
using MQTTnet;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace MqttConnectManage
{
    public class MqttClientManage
    {

        public readonly List<IMqttClient> _clients = new List<IMqttClient>();
        public readonly string[] _serverAdr;
        private List<MqttClientOptions> serverOptions = new List<MqttClientOptions>();
        private readonly IMqttNetLogger logger;
        private readonly CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();

        /// <summary>
        /// 日志记录
        /// </summary>
        /// <param name="logger"></param>
        public MqttClientManage(IMqttNetLogger logger)
        {
            this.logger = logger;
        }
        /// <summary>
        /// 客户端连接信息
        /// </summary>
        /// <param name="brokerAddress"></param>
        /// <param name="port"></param>
        /// <param name="clientId"></param>
        /// <param name="username"></param>
        /// <param name="password"></param&