I need to add some more ethernet devices to my network. I'd like to keep the current router and the only possibility to add more interfaces would be USB ethernet / PCI ethernet adapters. I could also use a network switch instead and connect it to one of the current router ports and easily get a lot of new interfaces.
But I was wondering if one setup would be less secure than the other one. It breaks down to the configuration I guess. The router does normal NAT'ing and each port currently provides a different network. My goal is to isolate the different connected devices so they can't communicate with each other. A dumb switch wouldn't do any good while managed switches provide some isolation as far as I know but I don't know if it comes close to the one provided by a router. If I go for the router and switch setup is there also anything I need to change on the router side?