OSDev.org

Just to note, the Watchdog Timer does fire as an NMI
Non Maskable Interrupt

The current state of things is that Windows 10 no longer boots, and cannot be repaired. I can still make RDOS startup and stay up by booting up the repair. Still, the Realtek RTL8169 compatible card only advertizes a PCI bar that refers to a memory location, and when mapping it, it's obvious it's not the operational registers. I cannot verify that it still works in Windows 10 since it no longer boots.

Not sure how to advance with it. I could go to the shop and tell them it doesn't work, or I could buy a USB-network card and write a driver for that instead.

There is some possibility that the RTL network card actually uses the RTL8100 type of interface in memory-mapped mode. At least that could explain why the NIC address is zero as with that chip the address is read using EE accesses and then programmed to the chip. It's probably worth investigating.

Solved the issue with the network card (it was rather stupid and I assumed the network function was always the first PCI function in a device, which was not the case with the Acer laptop), but the original issue is still there. After Windows no longer can be repaired, I setup a supervisor password in the BIOS, and then could permanently delete Windows secure keys, deactivate the security module and disable it. At the moment, it seems like I only need to boot into the repair utility, select to boot from UEFI USB from within it, and then RDOS will stay up forever. Not ideal, but it would work for my purposes as the system will always be on.

I solved the issue with the restarts by using a newer version of ACPICA (I used a 2011 release previously, and managed to go up to a 2015 release), and pretended to be all Windows versions from the latest ACPICA release. So it seems like the laptop has a BIOS that restarts the computer if Windows 10 is not running.