Some phones support the hardware back button and this may disturb the designed navigation experience that has been implemented in the application. You can override this behavior on Android (iOS does not support a hardware back button) with the following code that has to be placed in the MainActivity.cs of your Android root folder after onCreate method.
The result should look like below. After this action the hardware back button will have no effect and the whole navigation can be performed through the application.
In order to install successfully a chain certificate (in my environment it was issued by Entrust) on a Red hat you should edit the following entries in the /etc/httpd/conf.d/ssl.conf apache file.
#Server Private Key
#Server Certificate Chain
After the changes you should restart apache so that the changes take place. Keep in mind that if the certificate is password protected, you will be asked for an ssl passphrase that you should provide in order for the restart to be completed.
service httpd restart
You can ensure that the certificate is installed successfully by using the following command: