I don't know about this, but I'll give you an idea. You can turn on all the computers, then turn them off one by one, look at the work light on the switch, and then label them one by one (or turn them off and on one by one). 2. I thought of another way, turn on all the computers, then turn on the online neighbors to look at the online computers, and then unplug them to see which computers are offline. You can also chat on the LAN.