Proxmox on NUC8I5BEH

submitted by Guadin

I recently acuired a secondhand NUC8I5BEH and installed proxmox on it. But it randomly is unreachable from my LAN. There are no errors in syslog. When I connect a monitor there is no signal. So the NUC seems crashed. The fan is spinning and the LAN lights are on. It's not viewable on my unifi controller and it's not pingable. Where can I start looking for the problem?

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Bitswap , edited

Try adding a HDMI dummy plug. Older Intel NUC's (8th gen and earlier) have an issue that's fixed (but always seems to come back...) where they don't like functioning headlessly (without a display connected.)

Edit: Also, make sure your BIOS is uptodate.

Guadin [OP]

Hmm, this does sound like it makes sense. I got the feeling that as soon as I removed the monitor it would stop working in a couple of minutes. But I thought that couldn't be. Thanks for the tip! Going to see if that helps and I'm going to update the BIOS.


First try an HDMI dummy plug, in case the thing doesn’t dig no screen (classic intel firmware)

Then try Debian + Incus, less Proxmox shims to go wrong. Install Incus via the “zabby” repo mentioned on the incus install page. Search for “LXD” if Incus help/guides aren’t enough for you, they’re the same thing (for now). Providing an ISO in Proxmox is really clunky, and incus smooths that out so nicely. And again, less Proxmox shims to go wronk

Guadin [OP]

Going to try both. Someone else mentioned the dummy HDMI plug as well, so I got good hopes for that. Also going to look into Incuss. Never heard of it before.


It accomplishes the same thing as Proxmox (VMs and LXC containers, which are “lite VMs” for if you wanted a Linux VM), I recently learnt about it too! It is new, but it was backed by Canonical up until the LXD/Incus split so it’s very solid. Split because Canonical tried to control LXD heavily, so they forked and renamed it Incus.

I just used Incus and it’s very nice, use the profiles to create a profile for “GPU pass through” and “macvlan”, among others you’ll find you want. Then make instances as needed! It was easier for me to use than Proxmox.


Try following some of the advice in this thread. Hardware tests if the BIOS supports it. Maybe try underclocking or undervolting the CPU is BIOS supports that. If you can pull a RAM chip and test with just one, then test the chips individually in each slot, that'd be something worth trying. I'm shooting from the hip, but these are things that could help isolate a possible hardware issue.


First thing I would do is boot a live Ubuntu image from a USB. Make sure the hardware all works as expected.

Guadin [OP]

Thanks, will do.


Try a live Proxmox USB, it's what I did when my machine went unresponsive. Allowed me to look through the logs of the OS when it hadn't booted to find out what went wrong.

For me it was that I had put my USB HDDs in via Fstab and one had died, which made Proxmox unbootable until I hashtagged the lines out in fstab.


Any chance you are using a Thunderbolt device such as a network adapter or external drives? I had the issue on a NUC 10 where it would randomly drop the TB devices every few weeks and occasionally appear to be frozen. The latest firmware update finally took care of it.

Guadin [OP]

I don't think so. I do have a keychron keyboard, but that's just USB C I believe.

Decronym , edited

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

Fewer Letters More Letters
LXC Linux Containers
NUC Next Unit of Computing brand of Intel small computers
NVMe Non-Volatile Memory Express interface for mass storage

[Thread #800 for this sub, first seen 12th Jun 2024, 06:55] [[FAQ](] [[Full list](] [[Contact](] [Source code]


Plug it into a monitor or TV and keep an eye on the console.

I have an older NUC that will not cooperate with certain brands of NVMe drive under PVE…the issue sounds like yours where it would work for an arbitrary amount of time before crashing the file system, attempting to remount read-only and rendering the system inert and unable to handle changes like plugging a monitor in later, yet it would still be “on”.

Guadin [OP]

Thanks, going to do this as well. I had it on a monitor for a while and all looked fine while logged in on the console. Would be a bummer though if this would be true.