Vitux published a tutorial about finding devices in your network with nmap.

Find Devices Connected to Your Network with nmap

As Ubuntu users, we might want to know if we are the only ones using our network, especially wi-fi, or are there any other unwanted users leeching on our network bandwidth. This skill also comes in handy when we want to be sure that any hacker is not accessing our system by being connected to our network.

Find Devices Connected to Your Network with nmap