private void btn_Connect_Click(object sender, EventArgs e)
        {
            if (rb_Core.Checked)
            {
                _coreCreds = new CoreConnectionCredentials
                {
                    Hostname = tb_hostname.Text,
                    Port     = Convert.ToInt32(tb_Port.Text),
                    Username = tb_userName.Text,
                    Password = tb_password.Text
                };

                _coreCreds.SerizalizeCredsToFile();

                // Displays list of servers received from Core API to ListView
                try
                {
                    lbl_Loading.Visible = true;
                    ServerWrapper.ServersToListView(_coreCreds);
                    Logger.Log("Successfully connected to Core Server: " + tb_hostname.Text, Logger.LogLevel.Info, tb_hostname.Text);
                }
                catch (WCFClientBase.ClientServerErrorException exception)
                {
                    lbl_Loading.Visible = false;
                    Logger.LogError("Cannot connect to Core server " + _coreCreds.Hostname, _coreCreds.Hostname, exception);
                    MessageBox.Show("Cannot connect to Core server." + Environment.NewLine + exception.Message, "Connection Failed", MessageBoxButtons.OK, MessageBoxIcon.Error);

                    return;
                }
                catch (WCFClientBase.HttpUnauthorizedRequestException exception)
                {
                    lbl_Loading.Visible = false;
                    Logger.LogError("Cannot connect to Core server " + _coreCreds.Hostname + " Wrong credentials.", _coreCreds.Hostname, exception);
                    MessageBox.Show("Cannot connect to Core server. Incorrect credentials." + Environment.NewLine + exception.Message, "Connection Failed", MessageBoxButtons.OK, MessageBoxIcon.Error);

                    return;
                }
            }

            ServerWrapper.ServersListViewCreateColumns(lv_AgentsList);
            ServerWrapper.ExchangeListViewCreateColumns(lv_ExchangeServers);
            ServerWrapper.SqlListViewCreateColumns(lv_SQL);


            AddItemsToCbMailSize();
            GetGenParamsFromFileToGui();
            timer1.Interval = 3000; // Timer for UI update
            timer1.Start();
            lbl_Loading.Visible = false;

            // Hide Connection Page and displays ListView Page

            DisplayListViewPage();
        }