I would take regular backups so you can restore to a different controller in the event of a failure. Even missing backups, you could leverage the existing login information and "inform address" configuration to point all the equipment to a new controller.
Any chance you can make a new "How to Optimize a Unifi Network" video, please? Your last one is from 3 years ago and they are now on Unifi Network Server 8.0.28 which looks WAY different than it did 3 years ago.
A refreshed version is definitely on my list. Things have changed quite a bit since then. I plan to update both the AP setup and Optimization videos this year.
Typically, when this happens, I find myself logging into each device individually and updating the controller address manually. This usually causes them to pop right in the new controller. It's a bit of a pain... but as long as the old controller is powered down or uninstalled it works most of the time.
