By default UCP listens on port 443. To change the port UCP is listening on, navigate in the Web UI to Admin Settings > Cluster Configuration > Controller Port. This setting was introduced in UCP 2.0.0 and can only be changed through the Web UI. Applying a change to this setting will result in UCP controllers restarting and may briefly interrupt UCP availability. If using a load balancer for UCP, the load balancer will also need to be reconfigured to accommodate this change.
Alternatively, to change the configuration via the command line, issue the following from one manager:
docker service update --env-add CONTROLLER_PORT=443 ucp-agent