As mentioned, once you have created a Cloud Server with a custom template/OS, it cannot be accessed via RDP or SSH because the server, and in particular the network card, has not been configured with the new
IP address assigned. In order to be able to configure the IP you need to
access via the Recovery Console and manually configure the network card parameters with the parameters that are listed in the card for the individual Public IP assigned.
Of course, to be able to access the Cloud Server needs a RDP or VNC (
Virtual Network Computing) remote operating system in a Windows server or an SSH or NoMachine NX on a Linux server.
Similarly make sure you have a User Id and password to access and carry out all the necessary operations.