Failed to lookup UCP-controllers for version comparison check


for some reason I can’t open a new topic in the Datacenter subforum… anyway:
We’re trialing UCP (and Docker EE in general). After operating normally for a few hours, UPC UI doesn’t see any containers or statistics anymore, and it starts logging this:

Failed to lookup UCP-controllers for version comparison check: error during connect: Get https://:2376/v1.24/containers/json?filters=%7B%22name%22%3A%7B%22ucp-controller%22%3Atrue%7D%7D\u0026limit=0: x509: cannot validate certificate for because it doesn’t contain any IP SANs",“time”:“2017-11-17T08:01:42Z”

A complete reinstall (including leaving the swarm) fixes the issue, then it starts happening again. Any ideas? It would be quite bad if this happened in production.

… And after a setting change, UCP UI controller is dead, it keeps complaining about not being to able to reach the swarm manager.