KeyCloak Handshake causing timeout

Question

i have tried using socketsHttpHandler and httpclienthandler to connect to my api which requires a ssl. It was working fine in my local, but once i migrate to server, the first connection will always fail where handshake will take 15 seconds resulting in 408 timeout.

below are example of SocketsHttpHandler

        SslClientAuthenticationOptions sslOptions = new SslClientAuthenticationOptions
        { 
            RemoteCertificateValidationCallback = delegate { return true; },
        };

        using SocketsHttpHandler handler = new SocketsHttpHandler()
        {
            SslOptions = sslOptions,
            ConnectCallback = async (context, cancellationToken) =>
            { 
                IPHostEntry ipHostEntry = await Dns.GetHostEntryAsync(context.DnsEndPoint.Host);

                IPAddress ipAddress = ipHostEntry
                    .AddressList
                    .FirstOrDefault(i => i.AddressFamily == AddressFamily.InterNetwork);

                if (ipAddress == null)
                {
                    throw new Exception($"No IP4 address for {context.DnsEndPoint.Host}");
                }

                TcpClient tcp = new();
                await tcp.ConnectAsync(ipAddress, context.DnsEndPoint.Port, cancellationToken);

                return tcp.GetStream();
            }
        };
        using var httpClient = new HttpClient(handler);
        using var content = new FormUrlEncodedContent(GetHeaderSessionStart(login, password)); 
        content.Headers.Clear();
        content.Headers.Add("Content-Type", "application/x-www-form-urlencoded");

        HttpResponseMessage response = await httpClient.PostAsync(address, content);
        

below are example of HttpClientHandler

        var handler = new HttpClientHandler(); 
        handler.ClientCertificateOptions = ClientCertificateOption.Manual;
        handler.ServerCertificateCustomValidationCallback =
            (httpRequestMessage, cert, cetChain, policyErrors) =>
            {
                return true;
            };
        handler.CheckCertificateRevocationList = false; 
        using var httpClient = new HttpClient(handler);

i tried increasing timeout for httpclient, but it does not work either