Corsair EX400U Survivor Thunderbolt drive does not appear when waking from sleep

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Kubuntu 25.10
KDE 6.4.5 on x11 21.1.18
KDE Frameworks: 6.17.0
kernel 6.17.0.8-generic (64-bit)
Qt: 6.9.2
motherboard: MSI Tomahawk x870E
GPU: RTX 5090 (running 580 open driver)

No overclocking of CPU and the RAM is JEDEC, not Expo.

Problem:

Put the machine to sleep. Every other USB drive appears when waking from sleep except for the USB4/Thunderbolt drive (Corsair 4TB EX400U “Survivor”). Have to manually unplug it and plug it back in every time. Have tried restarting and shutting down but the behavior doesn’t change. Fully up to date according to Discover. Machine is in another room and this is extra wear and tear on the connector.

Did a Google search to find a solution and only found topics about Thunderbolt docks and monitors. So, I am asking here.

Relevant System Information:

Have other external USB drives that run at a lower spec (like USB 3.2) and they appear without issue.

This appears to affect either this drive specifically or USB4/Thunderbolt. Notably, Kubuntu only treats this drive as a Thunderbolt drive. The other drives do not appear in the Thunderbolt menu under System Settings. This Corsair is the only USB4/Thunderbolt drive I have to test but it’s brand-new and otherwise appears to be working without issue. File copying to the drive (1.5 TB) worked without issue and so does reading files from the drive. The only issue I’m having with it is it not appearing after machine sleep.

One of the USB 3.2 drives (2 TB in a metal Inland enclosure) is formatted as XFS and the Corsair is also formatted as XFS. Another USB 3.1 or 3.2 drive is formatted as ExFAT.

What I’ve Tried:

Restart, shutdown, update system via Discover, and Google search to try to find someone else with the same issue. All I found were reports about monitors and docks not awakening after sleep.

The drive appears as “Disconnected, Trusted” in the Thunderbolt System Settings after waking the computer from sleep and when I first plugged it in I chose to trust it permanently (not the exact wording but that’s the gist).

I assume there is some way to tell Kubuntu to reconnect disconnected Thunderbolt drives without having to resort to unplugging and plugging back in. The system is seeing the drive, after all, in System Settings. For some reason, though, the system isn’t reconnecting it after wake from sleep.

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Hello srs1111 :wave:

I believe this is a common USB4/Thunderbolt re-initialization issue after waking from sleep, not a fault with the drive itself—especially since the system still sees it as “Disconnected, Trusted”.

A few things you can try:

  1. Re-authorize Thunderbolt after wake
    Sometimes Thunderbolt authorization is not restored automatically after sleep. Try disabling and re-enabling Thunderbolt.

  2. Temporarily disable deep sleep for testing
    Some motherboards with USB4 don’t resume correctly from deep sleep. Disabling suspend temporarily can help confirm whether this is the cause.

  3. Try a Wayland session (if available)
    Since you’re using X11, power management behavior may differ under Wayland on Kubuntu.

Unfortunately, I don’t currently know of a reliable command that forces a Thunderbolt drive to reconnect after sleep without unplugging it, but the steps above help in many cases.

Good luck, and feel free to update us with any findings :star2:

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Hello,

Thank you for the suggestions.

I had tried step 1 but disabling Thunderbolt and re-enabling it (via the switch in the Thunderbolt screen in System Settings) didn’t work. I should have mentioned that I had tried that in my original post.

I was on Wayland initially and believe that the problem happened then, too. I will switch back to verify, though.

It seems odd that Linux doesn’t have a terminal command to handle this issue.

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Hello srs1111,

I did a bit of additional digging into this (including some AI-assisted research), and since Thunderbolt re-authorization and Wayland vs X11 don’t change the behavior, this does point more toward a kernel / USB4 resume issue, rather than a desktop or configuration problem.

A couple of extra things you could try, mainly for testing and narrowing it down:

  1. Force a Thunderbolt rescan via boltctl
    Sometimes the device can be re-enumerated manually:

    boltctl list
sudo boltctl enroll --all

    This doesn’t always work for storage devices, but it’s worth a try.

  2. Test a newer or older kernel (if possible)
    Since Kubuntu 25.10 uses a very recent kernel, regressions are possible. Testing another kernel can help confirm whether this is kernel-related.

If the issue is consistently reproducible, it may be worth reporting it as a kernel / USB4 resume bug, especially given that the device remains visible as Disconnected, Trusted.

Hope this helps narrow things down.

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