Some PCs, particularly workstations and servers, come with two Ethernet ports for practical reasons rather than as a cosmetic extra. The ports are designed to give the machine more networking flexibility, such as maintaining a connection if one link drops or keeping different kinds of traffic on separate networks.
Failover is one of the main benefits: if the PC is configured for it and one network connection goes down, the second port keeps the machine online. Link aggregation, also known as NIC teaming or bonding, can combine two Ethernet links into one logical connection, which can increase overall capacity. However, it must be supported and configured on both the PC and a managed switch, and it does not double your internet plan's speed—individual transfers generally stay limited to a single link's rate.
For many business users, the most valuable use is network separation. One port can connect to the regular office network while the other links to a dedicated storage device or a local network for specialized equipment. This approach helps isolate traffic for security or performance reasons and is especially relevant for cybersecurity work, network administration, or running a small business server.
For a typical home or gaming desktop, a second Ethernet port is more of a nice-to-have than a necessity. Simply plugging two cables in without a specific setup can even cause connection issues. If a router runs out of ports, an Ethernet switch is the more practical solution for adding more wired devices.