JUhalt

I can confirm that this was, in fact the issue. One other struggle I had along the way was getting into the BIOS. It isn't just hitting Delete, F12 or any other F-key. You have to hold Ctrl + F12 to get there. Otherwise you'll always see GRUB with no option to boot from USB, at least in my experience.

This person may have answered my question: My intention is to follow this:

Hi everyone, I just completed a fresh install of HexOS on a UGREEN DXP4800 Plus, and I’m running into repeated, seemingly random reboots. System specs: Intel Pentium Gold 8505 (5-core) 8 GB DDR5 RAM Built-in 128 GB SSD (used for the HexOS system install) 4 × 12 TB HDDs (data drives) The installation itself appeared to complete successfully. The system boots and reaches the Console Setup screen (the menu with options 1–10), and it is assigned an IP address. I’m able to access the web UI from my PC via https://deck.hexos.com, but after a short period the connection drops and I see a “server not available” / disconnected page. When I check the NAS physically, it appears to have rebooted on its own and is back at the Console Setup screen again. This cycle keeps repeating: boot → console menu → brief web access → reboot. At this point I’m not sure whether this is a hardware issue, a configuration problem, or something specific to the DXP4800 Plus platform. Any guidance on logs to check, settings to change, or known issues would be greatly appreciated. Thanks in advance for the help! Best