Chinese manufacturers offer a large choice of low-cost, fanless, servers. I chose one with more than enough power and four Ethernet plugs. Only two RJ45 connectors were needed but additional ones allow me to split the cluster in two sub-nodes and test consequences of inter-networks communication. For example, a kubernete-to-kubernetes cluster connection might be tested.

The 12V power required by the server will be delivered by the main power unit. It is just a question of finding the right plug …