Wake On LAN issue

Hi. In one location I have two desktops and three laptops. Only one of the laptops will wake via WOL which is due to the configuration limitations of the WiFi module according to the manufacturers (Lenovo and HP). Of the two desktops, only one will wake via WOL. The problem has been around for a couple of years and hasn't caused a major issue as I'm on site regularly. However it's now become a bigger problem. They are within arm's reach of one another and plugged into the same router. The setup is a TPLink modem running from a fixed wireless NBN (Australia) connection, which has a fixed public address. The two desktops have fixed IP addresses which are forwarded from the modem. The process so far:-

  1. The desktop that wakes is using port 10. The desktop that doesn't, has used ports 11, 12, 374 and 9741 without success.
  2. The mother board has been replaced in an attempt to qualify the LAN module, but nothing changed, which rules out the LAN module, but not Windows 10 as the SSD was reimaged.
  3. I've been through all of the BIOS and Windows 10 settings to match both of the desktops.

If there is some kind soul out there who may point me in a different direction, I would be grateful.

Cheers...