How to read variables from ASP.Net Core Multiple Environments?

Question

I’m trying to read from the properties appsettings file with different values, one for each environment. My files are as follows, appsettings.json, appsettings.Development.json, appsettings.Stage.json in case the system recognizes who the environment is working on and accesses the correct file, this part is working by which otherwise the system in the non working Stage environment as well as in the production environment for the customer. So this is not the problem, my problem is the following was developing and worked perfectly in the Development environment, but when I went to Stage, it did not work.

I have these codes currently:

appsettings.json:

"StringsConnection": {
    "canal": "plataforma-production",
    "link": "781115465H/1Tasdsdaaaa/K456546bb45654665fdg"
}

appsettings.Development.json:
"StringsConnection": {
    "canal": "plataforma-local",
    "link": "484ghj6ngfh/jg468fgh/dfg468df4g6864sdf84ds"
  },

appsettings.Stage.json:

"StringsConnection": {
    "canal": "plataforma-stage",
    "link": "dsf546/DSF86SD4F4DS/SAD6S8A4DSAdsf84dsa"
}

I am accessing the properties "channel" and "link"

apiControlerQualquer.Cs:

var canal= new collector_log
            {
                log = _config.GetValue<string>(
                   "ConnectionStrings:canal")
            };

var link= new collector_log
            {
                log = _config.GetValue<string>(
                "ConnectionStrings:link")
            };

in the controller I still have

  private readonly ApplicationDbContext _context;
    private readonly IMapper _mapper;
    private readonly IConfiguration _config;

    public Methods_Utils(ApplicationDbContext context, IMapper mapper, IConfiguration config)
    {
        _context = context;
        _mapper = mapper;
        _config = config;
    }

Startup.Cs:

public class Startup
    {
        //injeção de depencencias
        HelperController helper = new HelperController();

        public IConfiguration Configuration { get; private set; }
        public Startup(IConfiguration configuration, IHostingEnvironment env)
        {    
            var builder = new ConfigurationBuilder()
               .SetBasePath(env.ContentRootPath)
               .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
               .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
               .AddEnvironmentVariables();
            Configuration = builder.Build();
            this.Configuration = configuration;
        }

Program.Cs

public class Program
{        
    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();          
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
       WebHost.CreateDefaultBuilder(args)
           .UseStartup<Startup>()
          .ConfigureLogging((hostingContext, logging) =>
          {
              logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
              logging.AddConsole();
              logging.AddDebug();
              logging.AddEventSourceLogger();
          });              
}

The point is, I’m being able to access the values in the Development environment however, I’m not being able to access the values in the Stage environment, if anyone can help thank you.