Final answer:
The most likely problem with the two systems that do not wake correctly using Wake-On-LAN is incorrect BIOS settings, with network connectivity issues or hardware problems being less likely.
Step-by-step explanation:
If you've set up ten computers in a LAN and after updating them to the same version of Windows, eight computers wake up using Wake-On-LAN (WOL) but two do not, we need to consider several common issues that could be causing this problem. Given that majority of the systems function correctly, it indicates that the overall setup is correct. The failure of the two systems to wake up could most likely be due to incorrect BIOS settings. It is essential that the BIOS on each computer is configured to enable the WOL feature, as this setting is often disabled by default for security reasons.
Another less likely possibility could be related to network connectivity issues; if the two computers are not properly connected to the network, they wouldn't receive the WOL packets. Lastly, hardware issues such as a power supply problem or a faulty WOL feature on the network card could cause this issue, but these are less likely given that the computers are of the same make and model and would presumably have been tested for basic functionality before setting up the LAN.