Which of these devices contains many network ports, but does no other work than being a container for cable endpoints?

The device you are referring to is commonly known as a patch panel. A patch panel is a passive networking device that provides a central point for all the network cables in a location. It contains many network ports, allowing for the organization and management of cable connections. Its primary function is to serve as a container for cable endpoints, where it does not perform active tasks such as routing or switching data. The connections made in the patch panel can easily be rearranged as needed, facilitating maintenance and upgrades in network systems. Patch panels are widely used in data centers and telecom rooms for better organization of cabling infrastructure.