by defaulty on 9/10/21, 7:57 PM with 34 comments
by oneplane on 9/10/21, 9:31 PM
You can also do this with USB-A, get an USB-A controller that sends pause frames, plug it into a powered USB hub and connect to your computer. Unplug, watch the ethernet link still being online and suddenly the network dies. Mostly happens with Realtek USB Ethernet controllers.
This is a firmware feature so technically you can turn it off.
If you want to try it with PCI or PCIe: get a powered backplane or bifurcation board or thunderbolt-to-pci bridge. Connect/use as normal then disconnect the host while leaving power on. Same problem happens with controllers that send pause frames.
by the_mitsuhiko on 9/10/21, 10:43 PM
I have now heard that this problem happens with a lot of devices and the most common element in most of them is that people also have netgear switches on their network but not exclusively.
The most reliable workaround is to ensure that the USB-C adapter with an ethernet card in it is powered off when the laptop goes to sleep. Many do that if they are not also used for USB-C PD or whatever it's called.
by xg15 on 9/10/21, 10:34 PM
The what now? I've never heard of "PAUSE" frames before, but those sound like a feature just waiting to be exploited.
Do we know how common the behaviour to forward the frames is? This sounds like it could bring down any vulnerable public network of their choice by just logging on and sending that special packet...
by hectormalot on 9/10/21, 8:50 PM
To troubleshoot, I’d plug into the hub to have Ethernet connectivity, and the network would seem to work fine. Took me weeks of guessing before considering that a powered-but-disconnected USB hub could be the culprit.
Odd that this is an issue across so many vendors. Perhaps they share a chip, but still, it reads as a mistake on the Hub as well as the Switch side of things.
by Isthatablackgsd on 9/10/21, 8:44 PM
Now I have Anker 3.1 Mini-Dock (without the ethernet), it works well but it has issues with HDMI. For whatever the reason, the system think that the HDMI is plugged in the hub whereas it is not. So, It cause a strange issue with multimonitor since the system believes that there is a second monitor plugged to it. But yet it couldn’t show the second monitor in the display setting but it insists that it is plugged.
by Quollified on 9/10/21, 9:32 PM
I'm guessing a lot of the manufacturers just ended up using the same chip for their docks/hubs, and some manufacturers just don't care if there was a firmware update from the chip vendor.
by citrin_ru on 9/10/21, 10:37 PM
TP-Link (or more specifically Atheros AR8327 used inside it) here is likely breaks a IEEE standard (may be even the most basic one - 801.2d), but when no-one send pause frames this goes unnoticed.
As workaround now don't connect power to the hub and instead connect charger to a laptop directly (if a hub is powered you can connect only one cable to s laptop to get both - power and external USB+Ethernet).
by procarch2019 on 9/10/21, 8:53 PM
The one difference I see is that the docking stations are meant to be independently powered and I think it has its own fan. I’m sure the internals are different too, but I don’t know how. Curious if anyone knows more about the difference between the hardware/firmware on the hubs vs the stations.
by jzwinck on 9/10/21, 10:35 PM
by cbhl on 9/10/21, 8:46 PM
by readams on 9/10/21, 8:56 PM
by recursivedoubts on 9/10/21, 8:47 PM
five years ago I would have said five years
now I'd say 10
by markstos on 9/10/21, 8:48 PM