I'm using macOS 10.15.6 and windows 1909, the led of c100c is off when my pc fall sleep in both macOS and windows. WOL won't work after fall sleep and shutdown.
I can't with MacOS but for Windows 10, make sure you're on driver 2.1.21.0 (or newer).
In Device Manager for the NIC, on the Power Management tab, I have the following options set:
[x] Allow the computer to turn off this device to save power (you could try unchecking this, but for me, it works with it enabled).
[x] Allow this device to wake the computer
[ ] Only allow a magic packet to wake the computer (this one is unchecked)
On the Advanced tab, ensure that:
Wake from power off state == Enabled
Wake on Link == Disabled
Wake on Magic Packet == Enabled
Wake on Pattern Match == Enabled
Wake on Ping == Disabled***
*** - I have it disabled because I have a busy network with lots of scans but you could enable it if that's your thing.
Possibly also involved, in Control Panel -> Power Options -> Change Plan Settings (for your selected power plan) -> Change Advanced Power Settings -> PCI Express -> Link State Power Management -> Setting should be set to "Moderate power savings" of "Off". I am unsure if Maximum Power Savings will remove power from the slot when asleep. My system is set to "Moderate".
In addition to that, you may also have to check your BIOS settings for power management such as ErP (disabled) and "Power on by PCI-E" (enabled).
WOL requires the card, the OS, and the motherboard to all be in agreement. Motherboard/BIOS support for this is probably the biggest variable where you're most likely to run into issues.
When my system is asleep, the NIC link is still up (the NIC lights remain on and my managed switch still shows the port state as up) and the IP is still pingable.
I am able to send the appropriately crafted packet to wake the system from sleep.