You have two options to move your existing provisioned Amazon Redshift cluster into a different subnet:
Use an existing subnet group.
Create a new subnet group that contains the subnet to move the provisioned Amazon Redshift cluster into. After you have a subnet group with the preferred subnet, restore your cluster from a snapshot. Be sure that there's only one subnet in the subnet group. Otherwise, Amazon Redshift might not launch the cluster in that specific subnet.
To move your Amazon Redshift cluster into a different subnet group, perform these steps:
Navigate to Network and security to view network details. The Network and security information shows you the subnet group that's being used.
Under the Properties tab, navigate to Node IP addresses. This section has information that helps you verify the subnet that's in use. The listed subnet must be from your subnet group.
Subnet best practices
When you move your Amazon Redshift cluster into a different subnet, consider the following best practices:
Configure your cluster subnet group so that the subnets reside in a homogenous network. In a homogenous network configuration, all the subnets that belong to that group share similar networking rules and perform as a uniform network. A homogenous network configuration also minimizes any connectivity issues that can occur when you move your Amazon Redshift cluster into a different subnet.
Be sure that there are enough IP addresses in each of your subnets within the subnet group. If there aren't enough IP addresses in subnet, then your cluster launch might fail. To resolve a launch failure, delete any unused elastic network interfaces. Or, you can move your AWS resources into a different subnet. To do this, choose a different subnet group.