The SSL connection could not be established, see inner exception. c# post request

Question

I have a simple POST request function. It doesn't give me any errors but when my friend tries, it gives him this error. I use Windows 11 and he uses Windows 7.

The SSL connection could not be established, see inner exception.

So the code looks like

public class WebRequest
{
    private static HttpClient HTTP = new HttpClient();
    public static async Task<(bool,string)> Post(string url,StringContent data)
    {
        string result = "";
        string errorMessage = "";
        bool IsError = false;
        try
        {
            
            result = await(await HTTP.PostAsync(url, data).ConfigureAwait(continueOnCapturedContext: false)).Content.ReadAsStringAsync();
        }
        catch (Exception ex)
        {
            errorMessage = "Error1:" + ex.Message;
            IsError = true;
        }
        return (IsError, result);
    }
}

Then I searched through the internet and tried these and didn't work: 1:

private static HttpClientHandler clientHandler = new HttpClientHandler()
{
     ServerCertificateCustomValidationCallback = (message, cert, chain, sslPolicyErrors) => true,
     SslProtocols = System.Security.Authentication.SslProtocols.None
};

private static HttpClient HTTP = new HttpClient(clientHandler);

2:

ServicePointManager.Expect100Continue = true;
            
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls13;    

3:

ServicePointManager.ServerCertificateValidationCallback = delegate (object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
            {
                return true;
            }; 

If it helps here is the inner Exception :

System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.
 ---> System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception.
 ---> System.ComponentModel.Win32Exception (0x80090331): Ortak bir algoritma kullanmadıkları için istemci ve sunucu iletişim kuramıyor.
   at System.Net.SSPIWrapper.AcquireCredentialsHandle(ISSPIInterface secModule, String package, CredentialUse intent, SCHANNEL_CRED* scc)
   at System.Net.Security.SslStreamPal.AcquireCredentialsHandle(CredentialUse credUsage, SCHANNEL_CRED* secureCredential)
   at System.Net.Security.SslStreamPal.AcquireCredentialsHandleSchannelCred(SslStreamCertificateContext certificateContext, SslProtocols protocols, EncryptionPolicy policy, Boolean isServer)
   at System.Net.Security.SslStreamPal.AcquireCredentialsHandle(SslStreamCertificateContext certificateContext, SslProtocols protocols, EncryptionPolicy policy, Boolean isServer)
   --- End of inner exception stack trace ---
   at System.Net.Security.SslStreamPal.AcquireCredentialsHandle(SslStreamCertificateContext certificateContext, SslProtocols protocols, EncryptionPolicy policy, Boolean isServer)
   at System.Net.Security.SecureChannel.AcquireClientCredentials(Byte[]& thumbPrint)
   at System.Net.Security.SecureChannel.GenerateToken(ReadOnlySpan`1 inputBuffer, Byte[]& output)
   at System.Net.Security.SecureChannel.NextMessage(ReadOnlySpan`1 incomingBuffer)
   at System.Net.Security.SslStream.ForceAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Boolean receiveFirst, Byte[] reAuthenticationData, Boolean isApm)
   at System.Net.Http.ConnectHelper.EstablishSslConnectionAsync(SslClientAuthenticationOptions sslOptions, HttpRequestMessage request, Boolean async, Stream stream, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at System.Net.Http.ConnectHelper.EstablishSslConnectionAsync(SslClientAuthenticationOptions sslOptions, HttpRequestMessage request, Boolean async, Stream stream, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.ConnectAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.CreateHttp11ConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.AddHttp11ConnectionAsync(HttpRequestMessage request)
   at System.Threading.Tasks.TaskCompletionSourceWithCancellation`1.WaitWithCancellationAsync(CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.GetHttp11ConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
   at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpClient.<SendAsync>g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken)
   at System.Net.HttpWebRequest.SendRequest(Boolean async)
   at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)