Question NIC lights go off when computer is in sleep mode, yet on when the computer is off

[mikeymikec]

If the mods think that this topic is better suited to the networking forum then so be it, but I think it's a more power-related query.

A computer that I built back in around 2016-2017, Skylake processor, ASUS H170M-PLUS motherboard had a bit of a curious issue that when the computer was brought out of sleep mode, the NIC would sometimes not connect to the network. I tried updating drivers but it didn't help.

The solution I have found which appears to work is to disable 'allow the computer to power down this device to save power' in the driver settings in Device Manager.

What I find really strange though is that logically with this setting disabled, the NIC should remain active while the computer is in sleep mode, right? Yet the NIC lights go off while the computer is in sleep mode, then to make matters stranger, when the computer is shut down (though obvious with live mains still connected), the NIC lights are on.

Any thoughts on this one? At the end of the day I don't suppose it matters much as everything appears to work, I just think it's really bizarre!