Programs.cs

        public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .Build();
    }

　　↓

        public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()

               // 追加ここから
               .UseKestrel(options =>
                  {
                    options.Listen(System.Net.IPAddress.Any, 5000);
                  })
               // 追加ここまで

                .Build();
    }