Shared network UI constraints prevent VR IP from matching gateway IP

[llukeell]

The required feature described as a wish

When creating a shared network, the CloudStack UI enforces two mutually exclusive constraints:

Gateway IP cannot be within the guest IP range
Virtual router IP must be within the guest IP range

This makes it impossible for the VR IP and gateway IP to match. As a result, the VR health check (gateways_check.py) fails permanently since nothing responds at the gateway IP in a virtual environment.

Steps to reproduce:

1. Create a shared network in a Security Group zone
2. Attempt to set the VR IP to match the gateway IP
3. UI returns error: The gateway ip should not be part of the ip range being added
4. Attempt to set VR IP outside the guest range
5. UI returns error: Router IPv4 IP provided is not within the specified range

Expected behavior:
Allow the VR IP to be designated as the gateway IP, or provide a supported configuration path where the VR IP and gateway IP can match.

Workaround:
Manually update nics.gateway and vlan.vlan_gateway in the database to match the VR's assigned IP.

CloudStack version: 4.22.0.0
Hypervisor: KVM
Zone type: Security Group zone

[boring-cyborg]

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