Nextcloud - Error 504 and FPM pool down when syncing large file

Hi,

I am hosting an up to date Nextcloud with Yunohost on a Proxmox virtual machine, with data directory NFS mounted.

When syncing large file (more than 20GB) with Windows sync client, Nextcloud is crashing at some point, producing a 504 HTTP error. Restarting PHP does not seem to help and i have to reboot the machine.

I’ve tried several things, including raising timeouts, FPM pool resources (more child, more memory), nothing helps. Nothing relevant in Nextcloud logs when it happens, nor in PHP logs. It looks like memory exhaustion, but raising pool memory up to 6GB does not help and VM has lot of memory available.

Did someone encountered something like this ?

Regards.