Hi
@loady .
Your case reminds me the struggle I had for the last year with a very similar issue.
Let me start saying that I had all basics covered (open ports, fix arp/mac entry through startup script, windows fast boot, etc, etc, etc), and that I've been using wol for many many years so had a little bit of expertise regarding this topic.
One year ago, when I changed my pc, suddenly wol started to malfunction when pc was powered down (S5) for quite a time (+6 hours aprox, but random). Sometimes worked, sometimes not (most of times not). I tried literally EVERYTHING to get it solved, to obtain nothing but growing frustration. Leaving pc on standy mode is not suitable in my case for various reasons (kids, pets, etc.), so had it working from S5 was/is vital for me.
I know for sure it wasn't my router (rt87u) cause it worked perfectly fine before with my old rig, so it had to be my new motherboard/nic controller. Tried dozens of drivers, bios versions, etc... No luck. Contacted ASUS saying that my new moterboard (crosshair hero VII wi-fi) seems to have a bios bug cause wol is working erratically, and previous mobo (p8z68-v pro/gen3) worked just fine with same other network components. No luck either (didn't got much attention from them tbh).
So, long story short, after hundreds (literally) of tests, and seriously considering buying another brand/model of motherboard, I found the pattern of this bug and a way to workaround it:
Resume from S5 does not work ONLY when S3 state has been inmediatly active prior to S5 and no restart has been performed in between.
EXAMPLE 1 - WOL NOT WORKING (AFTER hours of being spent off):
1) POWER ON
2) SLEEP (S3)
3) RESUME FROM SLEEP
4) POWER OFF (S5)
5) WOL NOT WORKING
EXAMPLE 2 - WOL WORKING
1) POWER ON
2) POWER OFF
3) WOL WORKING 100%
EXAMPLE 3 - WOL WORKING
1) POWER ON
2) SLEEP (S3)
3) RESUME FROM S3
4) RESTART
4) POWER OFF (S5)
5) WOL WORKING 100%
Hope my quest may help you.
Regards!!!