How can I identify in Home Assistant when one of PCs on my network is one, based on it’s MAC address?
Simple idea of turninmg electrical supply to several devices that are assotiated with that PC. When PC is on/ off, Smart Relay will turn them on/ off.
Thank you.
Hi @Armit you could just use the simple Ping sensor.
EDIT
Great minds think alike. I was too slow 
Many thanks for quick response. I thought that Ping supports the IP addresses, nor MAC. For whatever reason that PC is not “pingable”, and instead of digging into why it does not respond to Ping I wanted to use its MAC address.
Hi @Armit if it’s a windows PC in the firewall icmp will need enabling. Then ping will work.
It worked like a charm. Thank you so much!
No problem just make sure your PC has a static IP address or you are using a DHCP reservation so it always has the same IP and doesn’t break you sensor.
Exaclty. Thank you again. So great to see such supportive people around.
Heads-up, simply shutting off the power to a PC is probably not something the OS is going to be happy with 
Exactly. My purpose is very different: I want to turn off power to several external devices (laser engravers, hubs, etc), which are controlled by PC. When PC is shutdowned, they will go off, too.
Used to do it with the current relay, but the Home Assistant is more elegant solution.
Ok that sounds logical