https://help.ui.com/hc/en-us/articles/204909754-UniFi-Layer-3-Adoption-for-Remote-UniFi-Network-Applications#8

set-inform http://ip-of-host:8080/inform

Also, be sure to set the inform url with the actual LAN IP of the controller (if you are using Docker for the unifi controller - which was otherwise using http://172.17.0.2:8080/inform as the url…)

Its the wrong IP address Grommit!