https://ubntwiki.com/guides/changing_the_default_site_in_unifi
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…)
It's the wrong IP address Grommit!
dpkg-reconfigure tzdata