That seems to have done the trick. I was afraid that there was some physical damage to the hardware.
With such a simple solution, it makes me think I just didn't look hard enough. :P
Anyway, thank you!
That is one way of doing the trick, by not allowing system shutting down the nic card in the first place.
Another way is trying to load a newer nic driver which will allow nic being shutdown when system goes to sleep but at the same time allow the nic card being completely woke up and online ready.
I just experienced a similar problem on my new Asus PC. I tried the same workaround before loading the new driver to fix the problem.