[OKD FCOS 4.15] Change Master and Worker IP Address to another subnet range

[parseltongued]

Describe the bug
I have an existing 3-node OKD FCOS 4.15 airgap cluster and i'm looking to export the entire cluster to a different IP subnet range (Old IP range: 172.17.12.* to New IP range: 192.168.20.*) but no fqdn change. My on-prem dns and dhcp servers, "Mirror registry for Red Hat OpenShift" and HAProxy are working on the new IP address range. The 3 master nodes have new IP addresses however they are not starting up (HAProxy 6443, 22623 is a flat red).

Although i've installed the cluster by specifying fqdn, suspecting it used the resolved IP to create the SSL cert, if so I need to recreate them, but I can't use oc commands because 6443 is not up.

How should I proceed and is there a proven procedure to change entire OKD cluster subnet?

Cluster environment
OKD Cluster Version: 4.15.0-0.okd-2024-03-10-010116
Kernel version: v1.28.2-3598+6e2789bbd58938-dirty
Installation method: Bare-metal UPI (Airgapped, self hosted quay)

[melledouwsma]

To my knowledge, there is no proven procedure for changing the IP addresses of all nodes in a cluster. Would it be possible to deploy three new nodes within the new IP range and then remove the existing nodes from the cluster? The contents of How to replace unhealthy master nodes in UPI on OpenShift 4.x may also be relevant in this case.

[parseltongued]

thank you. After reverting my VMs I am now facing another bigger issue would raise as another bug.