Hi, I'm looking for help in diagnosing/fixing the cause of disconnects to a thunderbolt/USB PCIE enclosure I recently added to my system. I moved my network nic out my case to make room for another video card. The system works perfectly when I first boot up (I can connect to Unraid through the nic and pass it through to my VMs no problem) but if I leave it running for a day or so I find the nic has disappeared. The unraid system itself is still responsive and I can log in and reboot via console using a directly connected monitor, but I completely lose networking to unraid and cannot connect to the web UI.

I feel like the system is putting the enclosure to sleep and then not able to wake it back up, but nothing I've tried so far seems to fix the issue.

Details:

-OS: Unraid 7.3.2

-CPU: Intel Core Ultra 285k

-Motherboard: MSI z890-p board running July 8 bios

-Nic: Mellanox ConnnectX-4 (MT27710) 2-port PCIE nic

-Thunderbolt Enclosure: OWC Mercury Helios 5S (connected via Thunderbolt 4 to the Motherboard)

I've included Diagnostics as well.

Any help would be greatly appreciated!

papyri-diagnostics-20260815-1132.zip

The diagnostics show that this is not starting as a Mellanox driver failure. The complete Helios connection drops: its USB hubs disconnect, followed by the Thunderbolt retimer and device. Only then do both Mellanox functions report that their PCI slot is unavailable.

The enclosure reconnects a few seconds later, and the PCI bus is rescanned, but the Mellanox card does not recover because PCI reads still fail. The entire enclosure then disconnects and reconnects twice more. Rebooting fully restores the card.

This also does not appear to be normal system sleep or USB autosuspend. There is no suspend event in the log, and USB autosuspend and PCIe port runtime power management are already

disabled. ASPM L1 does remain enabled by the BIOS across the Thunderbolt path, however.

I would suggest the following tests:

1. Temporarily use the onboard Realtek NIC for management so the server remains accessible when the Mellanox disappears.

2. Confirm whether the Helios power LED or fan cycles when the problem occurs.

3. Reseat the card, Thunderbolt cable and enclosure power connection. Test with the supplied short certified cable or another certified Thunderbolt cable.

4. Run the enclosure fan at its higher setting for comparison.

5. If possible, install the Mellanox card internally and run it for longer than the usual failure interval. If it remains stable internally, that would strongly point to the

enclosure, cable or Thunderbolt path.

6. Check with MSI and OWC for BIOS, Thunderbolt NVM and Helios firmware updates. It would also be worth asking OWC whether the MCX4121A-ACAT is qualified for this enclosure.

7. If the BIOS provides an ASPM or Thunderbolt power-management option, disable it for one test. Adding pcie_aspm=off may not be sufficient because current Linux can leave the firmware’s existing ASPM configuration unchanged.

USB Manager is installed, but its messages occur after the kernel reports the physical disconnect, so it does not currently look like the cause. A Safe Mode test without USB Manager/

USB-IP could still be tried later if the physical, firmware and internal-card tests are inconclusive.

Thank you for checking through everything. Let me confirm some of the items the next time the issue occurs. What I undestand now is+

2) Fan spins but I do not see the LED

3) I've reseated the card now and will try again (and if that doesn't work I'll try going with the original cable

4) Fan is already on high and I have a separate 12mm fan blowing over it as well

5) The card was originally internal and functioned normally there as well as when I've returned it internally since so as you mention, I believe its somewhere between the motherboard and the enclosure

6) I have the latest bios updates for the motherboard and enclosure does not have any additional firmware etc (I haven't asked about the card but from their site it looks like as long as its physically compatible it should be OK

7) BIOS settings are what give me the most concern. I thought I had gotten everything for PCIE and USB settings but I just noticed there's a separate Thunderbolt ITBT RD3 setting I've now disabled in BIOS so hopefully that's what was giving me the issues.

Will post again if I continue having issues and thank you again!