SSL problem when calling API

App Platform
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1

When calling the API from our production server, we get the following error:

The request was aborted: Could not create SSL/TLS secure channel. Stack
trace: at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult
asyncResult) at
System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult ar)

When we run the code locally using IIS Express in Visual Studio, the code works fine.
I understand that this might be an issue with the web host, but they seem clueless so I am checking here as well. Any help would be greatly appreciated.

By the way, adding the first line didn’t make any difference.

public async Task<List<Ticket>> FetchRecentTicketsAsync()
    {
        System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;

        CNCSIMSERVERACCESS cNCSIMSERVERACCESS = new CNCSIMSERVERACCESS();

        var apiKey = cNCSIMSERVERACCESS.GetVariable("FreshDeskAPIkey");
        var oneWeekAgo = DateTime.UtcNow.AddDays(-7).ToString("yyyy-MM-ddTHH:mm:ssZ");
        var apiUrl = "https://cncsimulator.freshdesk.com/api/v2/tickets?updated_since=" + oneWeekAgo;
        var client = new HttpClient();
        client.DefaultRequestHeaders.Add("Authorization", "Basic " + Convert.ToBase64String(System.Text.Encoding.Default.GetBytes(apiKey + ":X")));

        var response = await client.GetAsync(apiUrl);
        var content = await response.Content.ReadAsStringAsync();

        if (response.IsSuccessStatusCode)
        {
            var tickets = JsonConvert.DeserializeObject<List<Ticket>>(content);
            return tickets.Where(t => t.UpdatedAt >= DateTime.UtcNow.AddDays(-7) && t.Status == 2).ToList();
        }
        return null; // Handle errors appropriately.
    }