Hi Juju, please provide us with more details/information about the configs and your system set up.

I've never build openstack with Juju, I know that's one way to do, but I've got a few questions. This could be a misconfiguration on the mappings external network to NICs or a routing problem, or, or, or...

-> on which release? Ubuntu 16.04/18.04? -> which IPv4 classes do you have? Any IP-addresses, ranges or CIDRs would be helpful to understand your network - you should translate them into non-real addresses...

In case of using neutron: -> how do you name your external network? -> how did you get access to the external network? e. g. linuxbridge-agent or s. e.? -> how is the ext. net. mapped to the NICs on the bare metal?

Did you check any logfiles? Usually there are a lot of hints, what the real problem is... And last, but not least: did you read the properly manuals ;-)?

Robert