It's a hop or junction, not necessarily an end point, often with a media change. Fibre to the node for example is fibre to the local distribution point, where it's usually switched to a copper medium for "last mile", which could be DOCSIS, VDSL2...etc.
Basically, all endpoints are nodes, but not all nodes are endpoints.
Most simply, a node is anything that can create or move traffic. A switch is a node, an (active) bridge is a node, a computer is a node, a modem is a node, a phone is a node...etc.
All depends on how you slice and dice. You mentioned lower transport layers - these days I don’t set up data centres and instead develop on air traffic control software so my mind is at the application layer.
All depends on how you slice and dice. You mentioned lower transport layers - these days I don’t set up data centres and instead develop on air traffic control software so my mind is at the application layer.