We can deploy a ipv4 only cluster just fine, but when we enable a dual-stack cluster we get this error:
error: Reason: Dual-stack cluster cannot be created with empty Machine Networks
https://github.com/openshift/assisted-service/blob/master/internal/cluster/validations/validations.go#L776

We have an external loadbalancer for our ingress & API traffic which is on subnet 10.123.127.0/24
Our machinecidr range is on 10.124.0.0/24.

When specifying userManagedNetworking: true it should not check if the machine CIDR range is not specified even for dual-stack clusters.

I cannot specify the machine CIDR range because then I get this error: No suitable matching CIDR found for VIP. It expects the Ingress / API VIP to be in the machine CIDR range which is not in our case.

https://github.com/openshift/assisted-service/blob/master/internal/network/machine_network_cidr.go#L73

So to summarise:
1. Allow not defined machine cidr range for dual-stack clusters as well.
2. OR allow Ingress/API vip outside of machine cidr range.

4.13.z

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1. Allow not defined machine cidr range for dual-stack clusters as well. 2. OR allow Ingress/API vip outside of machine cidr range.

This is a blocker for my customer since they cannot deploy a dual-stack cluster because of that issue