Since Windows is now booting, I would first back up anything important before reconnecting the other drives.
Your ROG Hyper M.2 card isn't itself managing the RAID. From your earlier DiskPart output, the two 4 TB drives were dynamic disks and the mirror was being managed by Windows.
I would therefore leave Intel RST/VMD Off and do not create a RAID volume in the BIOS.
Power the PC off and reinstall both 4 TB NVMe drives on the ROG Hyper M.2 card together. On the Maximus Z790 Hero, ASUS recommends installing the Hyper M.2 card in the PCIEX16(G4) slot; that slot can run the two M.2 drives as x4/x4, which needs to be enabled in the BIOS.
Once Windows starts, open Disk Management and select Action → Rescan Disks. Don't initialise, format, convert or delete anything.
If both 4 TB disks appear normally and the mirror is Healthy, leave it alone. If one is still shown as Foreign, post a screenshot of Disk Management before making any changes. Windows does provide an Import Foreign Disks option for dynamic disks, and Microsoft recommends that all disks belonging to a mirrored volume be connected together before importing them.
Since the PC's stability also seemed to change when you disconnected Ethernet, I would keep the Ethernet cable disconnected while testing the Hyper M.2 card. That way we're only changing one thing at a time.
