alias IP's and netplan and docker

[matt-seedata-io]

Hi there. I've got a connectivity/routing issue i can't unpick...

 - I start from a VM with a primary IP and several alias IP address. I can ping 8.8.8.8 from the VM, and from a docker container on it. All good.
 - i bind those alias IP using netplan, and reboot. (yes, i fix the cloud-init thing first). I can still ping from the VM, but docker fails

I'm trying to do this because i want to use those alias IP addresses to present docker containers to the network on their own IP addresses

Any ideas please?