I am also not sure how to deal with the trusted domain issue. It may work to get a shell (univention-app shell nextcloud) , install an editor and change /var/www/html/config/config.php directly. You may also watch out for other differences to the config.php outside the container.
We are going to install nextcloud on ubuntu 22.04 from the command line, it will save our time as we are providing all the database and admin credentials for installation. It will install nextcloud silently, we dont have to go through web setup. For detail Nextcloud Command line installation, visit this page.
Or, we can Inspect the Browser during accessing nextcloud url, we can easily see the protocol column from the Network tab, it will show h2 as the protocol which is http2.
For the most part, I simply paged my way through the Ubuntu 20.04 Server setup picking primarily default options, naming my server nextcloud and setting up my root username and password. On the Featured Server Snaps screen, I was delighted to see that there was an option for Nextcloud, but as a result of my experimentation I decided to recommend skip over install the Nextcloud Snap at this point.
One advantage for example is, that I could run a debian buster image on my debian stretch machine. This was necessary because nextcloud requires php >= 7.2 and that is not available in armbian stretch.
df19127ead