Hello Abdur Rahman M,
In your current Always On migration plan, the SQL listener must be created in the same subnet where the client applications will connect. Since your new physical nodes are in the 152.x subnet, the listener’s virtual network name and IP should also be provisioned in that subnet. The cluster itself can remain with its core IP in 150.x, but the listener is independent and can be assigned to a different subnet as long as the cluster has a network interface in that range. You simply need to ensure that the Windows Server Failover Cluster has a network resource in 152.x and then add the listener with an IP from that subnet.
Once you remove the old 2019 VM node in 150.x from the availability group, the cluster will still retain its original 150.x network, but that does not affect the listener or database connectivity. No additional action is required unless you want to fully decommission the 150.x subnet from the cluster, in which case you can safely remove that cluster network resource after the cutover. The critical point is that the listener IP must align with the subnet where the new primary nodes reside, so clients can resolve and connect without routing issues.
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Thank you,
HL.