Multiple requests for an API result in 500 Internal Server error

Question

I have an API that makes two requests on Microsoft services (POST and GET) that receive a code and bring some information about employees.

public async Task<string> AdquirirEmail(string codeAD)
    {
        var AcToken = await HttpClientPost(codeAD);

        var emailAdquirido = await HttpClientGet(AcToken);

        return emailAdquirido;
    }


 private static async Task<string> HttpClientPost(string codeAD)
    {
        var url = "https://login.microsoftonline.com/...";

        var dic = new Dictionary<string, string>();

        //PRODUÇÃO
        dic.Add("client_id", "MeuClientID");
        dic.Add("scope_user", "user.read%20mail.read");
        dic.Add("code", codeAD);
        dic.Add("redirect_uri", "URL");
        dic.Add("grant_type", "authorization_code");
        dic.Add("client_secret", "MeuClientSecret");

        var content = new FormUrlEncodedContent(dic);

        try
        {
            var response = await clientPost.PostAsync(url, content);

            var responseString = await response.Content.ReadAsStringAsync();

            var convertModel = JsonConvert.DeserializeObject<PostResponse>(responseString);

            var acToken = convertModel.Access_token;

            return acToken;
        }
        catch (Exception ex)
        {

            throw ex;
        }
    }

 //Request GET
    private static async Task<string> HttpClientGet(string acToken)
    {
        if (clientGet.BaseAddress == null)
        {
            clientGet.BaseAddress = new Uri("https://graph.microsoft.com/v1.0/");
        }
        
        var token = acToken;
        clientGet.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);

        var responseTask = clientGet.GetAsync("me");
        responseTask.Wait();
        var result = responseTask.Result;

        try
        {
            var readTask = await result.Content.ReadAsStringAsync();
            var convertModel = JsonConvert.DeserializeObject<GetResponse>(readTask);

            var email = convertModel.Mail;

            return email;
        }
        catch (Exception ex)
        {
            throw ex;
        }

    }

With this code I can perform multiple requests in development and homologation servers without problems, but when it arrives at the production server, I can do the first one, already in the second one it takes approximately 1m40s and brings "The Operation Was Canceled"it only works if I have an interval of approximately 1 minute from one to the other:

Does anyone know what can be prevented from multiple requests on the server?