Seems your network is down:
> Sep 04 06:10:50 pve-node-08 corosync[3659]: [KNET ] link: host: 11 link: 0 is down
Maybe there are more hints in syslog?
I can also imagine a problem with your network switch. Does it help if you restart the switch?
We modify some container sytem files on startup, so we need to know the exact OS version.
System updates are required to maintain security. If you do them manually or atomatic is up to you.
I assume you test with different storage types? VMWare file format vs. LVM-thin.
Talking about LVM-thin, it is known that first time block allocation is quite slow. My guess is
that this is the cause for the bad result of your benchmark.
This package is part of the "non-free-firmware" debian component. You need to enable that in your apt sources.list.
See https://www.reddit.com/r/debian/comments/11012k4/tip_all_nonfree_firmware_packages_have_moved_to/