Several of your nodes (i.e. hardware elements, processors, servers, containers, virtual-machines, firewalls, loadbalancers etc.) will have high importance or special meaning for the system.
In such cases you should explain those nodes, what there properties are and why they are so special for the system or its operation.
The arc42 template (section 7) contains subsections labelled “Infrastructure element” - which you can use to document or specify such details.