下面的前端 typescript 代码

import { HubConnection, HubConnectionBuilder, HubConnectionState } from '@microsoft/signalr';

export class WechatMpQrComponent implements OnInit {  
  private connection: HubConnection;

  constructor() {}

  ngOnInit(): void {
    this.connection = new HubConnectionBuilder()
      .withUrl(`${environment.baseUrl}/hubs/wechat-mp-auth`)
      .build();  
  }

  async start(): Promise<void> {
    if (this.connection.state !== HubConnectionState.Disconnected) {
      return;
    }

    this.status = WechatMpQrStatus.Loading;
    try {
      await this.connection.start();
      await this.connection.send('Initialize');
    } catch (e) {
      this.onError(`建立连接失败 ${(e as Error)?.message}`);
    }
  }
}

经常出现下面的错误

建立连接失败：Unable to connect to the server with any of the available transports. WebSockets failed: Error: There was an error with the transport. ServerSentEvents failed: Error: Error occurred LongPolling failed: Error