I've got a fix proposed for this, but the full fix may also require a fix for bug #1759946, otherwise moving a subnet will leave each interface with an IP address on the subnet confused about which VLAN it belongs to.
I've got a fix proposed for this, but the full fix may also require a fix for bug #1759946, otherwise moving a subnet will leave each interface with an IP address on the subnet confused about which VLAN it belongs to.