What device facilitates connections from multiple computers simultaneously?

The device that facilitates connections from multiple computers simultaneously is a hub. A hub is a basic networking device used to connect multiple Ethernet devices, making them act as a single network segment. When data is received on one port of a hub, it is broadcast to all other ports, allowing data to flow between all connected devices. This characteristic allows multiple computers to communicate within the same local area network (LAN) at the same time.

While switches and routers also connect multiple devices, they operate differently. A switch connects devices in a more efficient manner by directing data only to the specific device that needs it, rather than broadcasting it to all devices. A router serves a different purpose, as it connects different networks and routes packets of data between them, often including features like network address translation and firewall capabilities. A modem, meanwhile, is used to connect to an Internet service provider, converting digital data to analog for transmission and vice versa. Therefore, in the context of connecting multiple computers simultaneously within a LAN, a hub is the correct answer.