I could more moderatly express myself: "Nextcloud isn't the thing i needed"
Here is how my opinion on nextcloud got here:

How unwise me stored Files:

At my earliest era of using PC's I always stored my files on a USB drive.
As this drive was filling up I bought a 1Tb m.2 ssd and put it into a adapter (lookt like an oversized usb stick):

I even put a whole OS on there so I could boot from it on school PC's ans play games.
At some point (was still using windows then) I realized that i had one Terabyte of onedrive storage from the office Subscription i needed anyways.
I then copied all files over to it and started using onedrive for everything.

Onedrive sucks

Onedrive always was about the first thing i deleted immediatly from all of my windows Devices.
However now i decided to use it.
I remember Onedrive being very mediocre.
It worked, was kinda slow but totally usable.
At some point i had used almost all of the 1TB I had and also remember onedrive infinitely trying to sync.
It had some 100'000 Files from some minecraft Folder I copied about half a year earlier which just never synced (not after 10 Hours).
Arguably my fault....

This all got way worse when i switched to linux.
There is no official Onedrive Linux Client. The one I used was called onedrive-bin I think and it worked but was too unstable and asked me for login way too often.
I remember it also acting weird and not downloading the files I wanted it to.

Discovering Homelab

After discovering that homelabs are a thing and self hosting can be cheaper than paying for cloud services I searched for a a solution to my Storage Problem:
I quickly found Nextcloud and my head screamed at me that it was too bloated and my Company Laptop (my Proxmox Server at that time) could not handle it.

So I searched for a more lightweight alternative and found this:
https://filebrowser.org/
I set this up using docker and found it to be very fast and snappy. I also saw that it wasnt very actively maintained.
To my awareness there also is no sync client for it which was a deal breaker for me.

The next thing i tried to use was https://www.filestash.app/.
I watched some tutorials only to realized that the Functions in the UI from the tutorial to not be there.
Feel free to correct me but to my understanding filestash is only the frontend for different storage backends and not a all in one solution.?

Setting up and Using nextcloud

I then found Nextcloud (and Owncloud, Ocis I just thought they are all the same thing) to be the only ones fulfilling my needs.
So I setup Nextcloud and used it for quite some time.
I had quite the rough start because i tried the newest stable version of nextcloud which was Completely broken (many features such as uploading in the UI or settings).
My friend told me to downgrade to 27 I think, which worked fine.
After using it for some time I was happy until I wanted to upload a 30GB Qcow2 VM Image.
It always failed after about 3GB. I was pissed.

This is where i searched Hours for the solution to this problem. I also asked my Friend who is responsible for operating a large Nextcloud Instance in Production, he could not help me but game me another functioning compose.
I wasnt willing to migrate to the new Nextloucd with the working compose, now i realize that would've been smarter.
(New compose wasnt using the weird apache fpm i was using)

After some angry hours of googling:
I then found the bug which was actually not from Nextcloud but from the Apache Image:

I must also Praise Nextcloud for the many things that did work flawlessly:

• Sharing Files with my brother
• Sync Client (besides login spam on I3 Window manager)
• 2Factor authentication

Conclusion

Nextcloud for me was a pain in the butt to setup and maintain.
The initial setup was very fast but certain crucial features broke when i needed them to work.
At some point i needed some random Redirect URL and trusted IPs in my traefik config to revive it.
This was enough and so i searched for alternatives.

Syncthing

Confusing but exactly what I need.

Syncthing was all over the place on Reddit Posts about Nextcloud and alternatives ...
I then watched a couple of Youtube Videos only to be even more confused.

• Is there a server?
• How does it differ from nextcloud

So I decided to just set seyncthing up on a VM to test it out.
By doing this I started to understand how it works and being able to answer the above questions.
There is no Server.
For me these things make syncthing amazing:

• Peer to Peer (Syncthing gets faster with more devices)
• Selecting any folder on the device instead of having to put them all in one folder (e.g Nextcloud folder)
• speeeeeeeeeed
• Easy to maintain

This VM i setup to initially test syncthing turned out to be super handy. I decided to just share all folders from any device to this vm so that if this said device is Off the stuff is still on the VM.