Use Existing Private IP

Greetings,

I understand that you currently trying to create a new instance from the AMI created of the old instance and also want to use the Private IP of the old instance.

Yes, you can Preserve the Private IP of the old instance and attach it to a new instance by following the steps below.

1. Create an AMI of the old instance.

2. In the Networking tab of the old Instance click on the eni-interface assigned to the instance.

3. Select the ENI and Change the termination behavior of the Elastic Network Interface (ENI).

ENI ---> Actions ---> Change termination behavior ---> Uncheck “Enable” ---> Save

4. Terminate the old instance

5. Launch a new Instance from the created AMI.

Note: Select “Advanced Network Configuration” and add the network interface here, please make sure you are using the correct subnet.

6. The New Instance will have the same Private IP as the old one.

Below are some additional documents for your reference.

References:

[1] https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html

[2] https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/best-practices-for-configuring-network-interfaces.html