I cannot understand where those keys are, its a long time since I have done this stuff but you should be able to manually generate them. You haven't tried to cluster them have you?
No, i just installed a fresh Proxmox 6 and restarted the server... nothing more..
(Using OVH Proxmox 6 template)
Some info:
# systemctl status -l pve-cluster
● pve-cluster.service - The Proxmox VE cluster filesystem
Loaded: loaded (/lib/systemd/system/pve-cluster.service; enabled; vendor pres
Active: failed (Result: exit-code) since Mon 2020-06-01 21:11:01 UTC; 3min 40
Process: 1181 ExecStart=/usr/bin/pmxcfs (code=exited, status=255/EXCEPTION)
Jun 01 21:11:01 ProxmoxServer systemd[1]: pve-cluster.service: Service RestartS
Jun 01 21:11:01 ProxmoxServer systemd[1]: pve-cluster.service: Scheduled restar
Jun 01 21:11:01 ProxmoxServer systemd[1]: Stopped The Proxmox VE cluster filesy
Jun 01 21:11:01 ProxmoxServer systemd[1]: pve-cluster.service: Start request re
Jun 01 21:11:01 ProxmoxServer systemd[1]: pve-cluster.service: Failed with resu
Jun 01 21:11:01 ProxmoxServer systemd[1]: Failed to start The Proxmox VE cluste
lines 1-11/11 (END)...skipping...
● pve-cluster.service - The Proxmox VE cluster filesystem
Loaded: loaded (/lib/systemd/system/pve-cluster.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Mon 2020-06-01 21:11:01 UTC; 3min 40s ago
Process: 1181 ExecStart=/usr/bin/pmxcfs (code=exited, status=255/EXCEPTION)
Jun 01 21:11:01 ProxmoxServer systemd[1]: pve-cluster.service: Service RestartSec=100ms expired, scheduling restart.
Jun 01 21:11:01 ProxmoxServer systemd[1]: pve-cluster.service: Scheduled restart job, restart counter is at 5.
Jun 01 21:11:01 ProxmoxServer systemd[1]: Stopped The Proxmox VE cluster filesystem.
Jun 01 21:11:01 ProxmoxServer systemd[1]: pve-cluster.service: Start request repeated too quickly.
Jun 01 21:11:01 ProxmoxServer systemd[1]: pve-cluster.service: Failed with result 'exit-code'.
Jun 01 21:11:01 ProxmoxServer systemd[1]: Failed to start The Proxmox VE cluster filesystem.
--------------------------------------------------------------------------------------------
# journalctl -u pve-cluster
-- Logs begin at Mon 2020-06-01 21:10:45 UTC, end at Mon 2020-06-01 21:15:41 UTC. --
Jun 01 21:11:00 ProxmoxServer systemd[1]: Starting The Proxmox VE cluster filesystem...
Jun 01 21:11:00 ProxmoxServer pmxcfs[1099]: [main] crit: Unable to get local IP address
Jun 01 21:11:00 ProxmoxServer pmxcfs[1099]: [main] crit: Unable to get local IP address
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Control process exited, code=exited, status=255/EXCEPTION
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Failed with result 'exit-code'.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Failed to start The Proxmox VE cluster filesystem.
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Service RestartSec=100ms expired, scheduling restart.
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Scheduled restart job, restart counter is at 1.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Stopped The Proxmox VE cluster filesystem.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Starting The Proxmox VE cluster filesystem...
Jun 01 21:11:00 ProxmoxServer pmxcfs[1177]: [main] crit: Unable to get local IP address
Jun 01 21:11:00 ProxmoxServer pmxcfs[1177]: [main] crit: Unable to get local IP address
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Control process exited, code=exited, status=255/EXCEPTION
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Failed with result 'exit-code'.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Failed to start The Proxmox VE cluster filesystem.
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Service RestartSec=100ms expired, scheduling restart.
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Scheduled restart job, restart counter is at 2.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Stopped The Proxmox VE cluster filesystem.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Starting The Proxmox VE cluster filesystem...
Jun 01 21:11:00 ProxmoxServer pmxcfs[1178]: [main] crit: Unable to get local IP address
Jun 01 21:11:00 ProxmoxServer pmxcfs[1178]: [main] crit: Unable to get local IP address
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Control process exited, code=exited, status=255/EXCEPTION
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Failed with result 'exit-code'.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Failed to start The Proxmox VE cluster filesystem.
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Service RestartSec=100ms expired, scheduling restart.
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Scheduled restart job, restart counter is at 3.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Stopped The Proxmox VE cluster filesystem.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Starting The Proxmox VE cluster filesystem...
Jun 01 21:11:00 ProxmoxServer pmxcfs[1179]: [main] crit: Unable to get local IP address
Jun 01 21:11:00 ProxmoxServer pmxcfs[1179]: [main] crit: Unable to get local IP address
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Control process exited, code=exited, status=255/EXCEPTION
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Failed with result 'exit-code'.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Failed to start The Proxmox VE cluster filesystem.
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Service RestartSec=100ms expired, scheduling restart.
Jun 01 21:11:00 ProxmoxServer systemd[1]: pve-cluster.service: Scheduled restart job, restart counter is at 4.
Jun 01 21:11:00 ProxmoxServer systemd[1]: Stopped The Proxmox VE cluster filesystem.
------------------------------------------------------------------------------------------
nano /etc/hosts:
37.187.xxx.201 ProxmoxServer ProxmoxServer
127.0.1.1 ProxmoxServer ProxmoxServer
Any ideas?