I deployed Load-Balancer-As-A-Service (LBAAS) in my lab OpenStack deployment early on, and it worked (setup in Horizon) as advertised (load-balancing inbound HTTP connections to multiple docker swarm nodes), until I broke the stack by fiddling with MTU settings.
This is a companion discussion topic for the original entry at https://www.funkypenguin.co.nz/note/openstack-lbaasv2-failed-connection-debugging/