Move to Nextcloud - Requirements
Project Link: Nextcloud
At first, there is a really good documentation provided by Nextcloud how to install, tune and secure a Nextcloud instance here and i recommend to read this documentation carefully. But i would like to share some points that were not clear for me at first.
I cannot answer the question of needed hardware for a self-hosted Nextcloud instance, because it depends on your needs. For a file server only, i think a Raspberry Pi 4 with a USB powered SSD would be enough. I personally host my instance on a Raspberry Pi 4 (8 GB) with an external NAS attached via SMB to the instance as my storage for my files. My database files are located at an USB attached SSD (250 GB) powered by a power adapter.
I recommend a 64bit OS as some Apps (this is how the extension are called in Nextcloud) are requires 64bit. A file server only setup would also be running at a 32bit system. Nextcloud recommend 64bit OS and PHP => 8.0 itself (as of Dec 2021). After switching from Arch Linux to Raspberry Pi OS i am now using Ubuntu 20.04 as my OS for the Nextcloud instance.
In this documentation i will use Apache2 as my web server and proxy. Nextcloud also delivers configuration files for other web server like NGINX.
SSL and access from outside of the local LAN:
If you are want to use your instance in your local LAN only, you can create a self signed SSL certificate. If you want to access your instance from everywhere i recommend a proxy server and certbot for obtaining the SSL certificate. I use this for sharing files with my family members, access my Calendar and Contact Data from mobile network and provide an access to my instance over the internet.