I assume your're working with the tenant 00000000000000000000000000000081, correct?
For this tenant id, no vrouter is existing on the Berlin node.
Without a vrouter you are not able to assign a floating IP to a VM. This is because we are using neutron instead of nova-network.
If you create a new vrouter it seems to better to set first the gateway before attaching the tenant network.

mm I thought that the external network was asociated to a virtual router. If I create a virtual router, do I have permissions to add my network to the virtual router? I think this behaviour is a bit strange.
Regards,
Henar

Please note that:

– a VM must be attached to a private (tenant) network which is connected to a router (you need to create that router and network/subnet in your tenant).
– The router's default gateway than can be set to either the "ext-net-public" or the "ext-net-federation" networks. After doing that you can associate a floating IP.from a public network.
– Two firewalls are between public Internet and your VM then: one you can control by setting a security rule for your VM instance, the other one must be configured by the node. Please inform us about the ports you need to be open.

I freed up 3 public IPs just a minute ago.