Got it, I’ll keep it my versions as is.
Well i do use nginx from Mainline-Repository (https://nginx.org)
php 8.3 out of original ubuntu sources and
MariaDB form original Repository (https://mariadb.org)
With this combination i do not face any of your issues.
Except maybe the PHP version, you could try 8.3 instead. But I highly doubt that this is the issue on a fresh install, without any additional apps installed, as NC31 generally is compatible with 8.4.
Which version?
Although MariaDB probably isn’t causing the issue, if you can’t even access the initial setup page via your browser.
That said, I would recommend using either 10.11 or 11.4. Avoid using any non-LTS versions or rolling releases to prevent potential issues in the future.
It’s likely not an issue with the versions of the software you’re using, but rather a configuration issue.
I did install it with Version 10.6 LTS
Yeah this should work as well, but I’d recommend using at least 10.11 if you start fresh.
I agree to 10.11 but when i did installation a year ago i was using that.
Current available LTS is 11.4
Yes, all currently supported LTS versions of MariaDB work fine with Nextcloud. With a newer version, you can simply wait longer before needing to update it. There might be some minor performance improvements with newer versions, but these are probably negligible for home users. 
Alright, here is an overall update.
I have downgraded PHP and have installed the following after purging my previous PHP config + modules
sudo apt-get purge php*
sudo apt install php8.3
sudo apt install -y php-common php8.3-{fpm,gd,curl,xml,zip,intl,mbstring,bz2,ldap,apcu,bcmath,gmp,imagick,igbinary,mysql,redis,smbclient,sqlite3,cli,common,opcache,readline}
PHP8.3-FPM service is confirmed active and enabled.
I will now config FPM adhering to this Digital Ocean guide, courtesy of @TheWojtek. I have also decided to bring the server w me during travel to continue working.
Anyone can see my active configs via GitLab
Thank you for all the help!
Try
sudo apt install -y php-common php8.3-{fpm,gd,curl,xml,zip,intl,mbstring,bz2,ldap,apcu,bcmath,gmp,imagick,igbinary,mysql,redis,smbclient,sqlite3,cli,common,opcache,readline}
And maybe try an actual guide for Nextcloud instead of just a general guide for PHP-FPM.
The most comprehensive guide I know is the following one. It’s in German, but that shouldn’t be an issue, even if you’re not a native speaker, since online translators exist: Nextcloud Installationsanleitung - Carsten Rieger
Also a good one (German, PostgreSQL): Nextcloud auf Ubuntu Server 24.04 LTS mit nginx, MariaDB/PostgreSQL, PHP, Let’s Encrypt, Redis und Fail2ban » DecaTec
A more simplistic one with Apache: How to Install Nextcloud on Ubuntu 24.04 Server
And still a very good option: GitHub - nextcloud/all-in-one: 📦 The official Nextcloud installation method. Provides easy deployment and maintenance with most features included in this one Nextcloud instance.
Should the user technically be nginx?
To confirm, the user and group owner for these PHP config files, specifically FPM, should be nginx?
I do agree to @bb77
Do use a specific guide for Nextcloud. I did used the DecaTec one. Its great. First time i did used as guide for Ubuntu 18:04. The DecaTec guide was updated every two years for all Ubuntu LTS. But i am native german speaker. So you may have another view on it if not native german speaker.
It’s www-data on Ubuntu
Also, the default webroot on ubuntu is /var/www/html
That may be a major issue, I have been changing ownership to nginx AND use /usr/share/nginx/html as my web root. I thought www-data and /var/www/html are specifically for Apache2?
I store my working nignx web server at /usr/share/nginx/html/, would I not store Nextcloud as /usr/share/nginx/html/nextcloud?
Well I wouldn’t call this a major issue, but rather something you learned
I will continue updates tomorrow! I have a flight. Thanks for all the help!
In this case you need to follow the NC install guide but use the directories you put your NC installation into (and you have set as the home dir for your Nginx virtual server.
And yes, it’s www-data on Ubuntu, just like I mentioned this morning 
Hello. I haven’t read the whole thread in details TLDR; but it seems it had been mainly focused on software versions.
Just to bring my testimony. My Nextcloud instance is for private/personal use and has been running for years, following all NC versions and several Ubuntu upgrades too (at least once Ubuntu upgraded to match the minimum PHP version required).
Well, in the end, I’m running Ubuntu 24.10 (can’t remember why I left the 24.04 LTS version. Maybe unrelated to NC), and upgraded from Nextcloud 30.x to 31.0 last week without major issues.
Php and Nginx are the default distro versions provided by the Ubuntu repo. Why bother when it’s not needed and better to stay with the official and maintained version from a reliable source.
So: Ubuntu 24.04 (/ 24.10) without alternative sources
- Nginx 24.0 (/ 26.0)
- Php 8.3.6 (/ 8.3.11)
- Mariadb-server 10.11.11 (/ 11.4.5)
Until you have a Nextcloud php page displayed, the source of the issue may appear in the webserver (ngnix or apache and php logs).
Good luck.
For the record :
Upgrade to Nextcloud 30
System requirements
- PHP 8.1 is now deprecated but still supported.
- PHP 8.0 is no longer supported.
- PostgreSQL 9.4 is no longer supported.
- MariaDB 10.3 and 10.5 are no longer supported.
Upgrade to Nextcloud 31
System requirements
- PHP 8.1 is now deprecated but still supported.
- PHP 8.4 is now supported, but 8.3 is recommended.
Did you open the local ports on the Nextcloud machine? Like ports 8080 or 8443 whatever your setup needs via ufw or whatever firewall you’re having on the box?