Update VM/LXC on different node

[donsilvia]

I have a 3-node cluster. Ultimate Updater is installed on only one node. The nodes are all set up as in the instructions: each node's hosts file has the other two nodes, and root on each node can ssh with key auth to the other nodes. awk '/ring0_addr/{print $2}' "/etc/corosync/corosync.conf" prints the IP addresses of all 3 nodes.

If I run update <ID> for a VM or LXC on the same node where the updater is installed it works. I can verify by logging into the guest and run apt update; apt upgrade, there will be no new packages. But if I run If I run update <ID> for a VM or LXC that is not on the node where the updater is installed, then log in to the guest and run apt update; apt upgrade, there are updated packages installed. In all cases, the output from update <ID> shows for example:

              Script is UpToDate
                 Version: 4.5.2

ℹ  Exit, if error come up, is disabled

ℹ  Update only LXC/VM 131 - work only on main host!

✅ Finished, all updates done.

🎉 All fine, have a nice day

Did I miss something in the setup? Or should I install Ultimate Updater on each Proxmox node?