hi, i know the Supported Linux distributions Debian 10 – 12 (recommended) and Debian testing Ubuntu 20.04 — LTS – 24.04 LTS (recommended) but wiould I be able to install this on 18.04?
Yes, you can install it there. But we have not tested it, and it might be that you get PHP errors when the system PHP is too old. In that case, you might have to set the system PHP to a newer version (even if I generally recommend avoiding that, but it's the only way for your case).
It would be nice to have options for turning off system metrics. In multi-server env it is almost useless, especially when Zabbix used.
System metrics are created and visualized for all servers, see monitor module. Just the Dashboard metrics are for the main server and you can configure if they shall be shown or not under System > interface > main config > misc. system metrics work perfectly fine on a multi server setup.
