I will be doing another kernel upgrade this Friday between 11pm-midnight requiring reboots of all machines.
As I feared, there were bugs introduced in NFS, particular an issue with delayed requests in NFSD causing the daemon to die (nfs server daemon). While I have not encountered this yet it is a documented problem so going to upgrade to fix.
Also some issues where introduced into KVM/QEMU used for hosting virtual machines. Again, I haven’t experienced these but it is a race condition and so just a matter of time.
With respect to Nextcloud, still no fix from the developers. I’m going to attempt a re-install while keeping the existing database.