How many Ethernet ports do I need before I should add a switch?

If the device count is only slightly above the router’s available ports, adding a switch is often the simplest answer. The main thing is to think about growth, power, physical layout and whether different types of devices should be kept logically separate. A router is there to manage connectivity and policy; it does not need to be forced into every local-network job.

Comset can help decide whether a four-port router is enough on its own or whether the cleaner design is a router plus switch. That usually becomes obvious once the connected devices are listed properly.