NextCloud "Error when assembling chunks, status code 504" for big files

Hi Everyone,

I am facing this issue when I'm trying to upload bigger files to my NextCloud. I definitely need to have the possibility to upload bigger files as I need to share files for video editing - it's not uncommon to have 20GB+ files. How can I solve this issue? I saw some forum posts where they are talking about an apache issue but that shouldn't be relevant to me. Not sure what information you need so I attached some screenshots to have some info about the system.

1. Running containers in Portainer

2. Basic system info (CPU, Kernel, etc.)

3. File systems

4. Disks

Thanks for the links, I checked them out but I'm not sure what to do with it to be honest. It seems like I will have some help during the weekend and hopefully he is going to help me figuring out what to do. I suspect I have some issues with encryption. I basically just want to turn it off but unfortunately it's not as easy as it is to turn it on.