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USB 3.0 extension cord running nearby can render Hub useless



My hardware is hub v2, I simply want to warn everyone who might have this problem as well.

FAQ: why would I need another beaming repeater if my zwave lock is already close to my hub?
All zigbee devices unresponsive
(Jimmy) #2

Huh? More details?


I accidentally run an USB 3.0 extension cord within 3 inches of the hub and all automations stopped working, nor can the hub see updates from sensors.

The other end of the extension cord is connected to SD card reader, I’m not sure whether it is relevant, through.

(Jimmy) #4

I can’t think of a reason that would have affected it. It was a usb extension connecting a card reader and a PC?


Sorry my bad, the other end of the extension cord is connected to PC and I’m actively reading data off the SD card reader.

After removing the extension cord and unplug it from my PC the hub start to operate normally again.


I’m sorry, I’m not buying this. The EM interference from a USB cable affected your hub? If it was that easy to disrupt you’d never be able to get a signal anywhere. When you say “automations didn’t work” you mean all your devices showed up as “unavailable”? Because most of your “automations” are not even stored on the hub. They’re in the ST cloud.


To clarify a little bit, update from sensors cannot reach hub and I cannot control any device when the interference is ongoing.

I doubt it would be to hard to reproduce the problem. Besides it is very close to the hub, within 3 inches, I guess that sort of make more sense.

If my theory is working it seemed I find a good way to disable non consealed security wireless sensors, hahaha.

I’ll try to see if sensors get interfered by USB 3 first. Definitely don’t want to try it on my hub again.

Will try to make a video if I have some time.


For ZigBee that may make sense. Early routers with USB 3.0 interfaces had to go into “low noise” mode which degraded USB 3.0 performance not to interfere with 2.4 GHz channels. ZigBee has overlap with the 2.4 GHz channels and can suffer the same interference. For Z-Wave, that shouldn’t have been impacted.


I’d like to point out that the article you link to says that the problem comes mainly from the port and that if it’s shielded that eliminates the problem. I did a quick search on Amazon and was not able to find a USB 3.0 extension cable that wasn’t shielded. So, I maintain, I’m not buying it.

(Eric) #10

@rolled54.Why , I’d like to know if the problem is repeatable. Thanks for posting.

(Jared) #11

What’s with all the doubters? How about you test it yourselves before you get your pitch forks out?

I believe it, USB3 is nasty noisy. That’s why a lot of wireless device manufacturers (mice and keyboards, etc) recommend NOT using the itty-bitty wireless receiver in a 3.0 port.


They do? I’ve never heard that. Can you provide a link to this advice from a wireless device manufacturer?

(Jared) #13

Too lazy to Google it yourself? Took me all of 30 seconds to find.


Yes, caused by interference at that port, not from the cable. They even say:
“as far away as possible from your USB 3.0 connector.” They don’t say anything about the cable going to your USB 3.0 device. The cables are shielded. Hence no interference. Sorry, I still call bunk on this one till someone shows me evidence.


It’s a known problem, we used to see it in an office environment. Most commonly somebody’s Bluetooth wireless mouse would stop working, But it can definitely affect zigbee equipment as well.

These days, pretty much all the cables you can buy on Amazon are shielded, but you can still get cheap ones from Alibaba or old ones from eBay that may not have the shielding.

As @Ryan780 mentioned, the Problem is usually much worse from the ports than from the cable, But the interference can occur up to 5 feet away from the port which is often more than the length of the extension cord, so what you think is interference from cable maybe interference from the laptop port at the other end. Or from the other device.

Intel did a white paper on the issue with examples back in 2012 that we used to leave with the local IT support guys if we identified the problem. They would use it to tell office employees not to use the USB 3.0 ports on their laptops in certain restricted zones (usually where we had sensors deployed).

So… Yes, it could happen, although usually the interference is from the ports of the devices at each end of the cable, not from the cable itself.

Also, If you’re buying cheap cables, stop. :wink: Quality cables are usually worth the investment. There’s quite a bit of engineering that goes into them.


It seemed I can consistently reproduce the problem.
PC is within 5 meters of hub.
USB 3.0 SD card reader connected.
Actively read/write data to or from device.

Zigbee devices will stop working.

( - Make your home your butler!) #17

Impressive paper, yeah it looks like 3.0 causes some pretty serious interference even with shielding of the ports and cables. Wow, how did this pass muster with IEEE? Looks like any 2.4Ghz RF devices within a few feet of the USB 3.0 port / cables /end devices are in trouble.


It’s a problem that didn’t occur that much in the lab where everybody placed things kind of automatically, all the equipment was consistent in release number, and everything was pretty well-made. (Notice that if you stretch the cables out the full length it’s less likely to cause interference than if it’s coiling back on itself. Engineers tend to do that automatically. Other people not so much. :wink: )

It started showing up with cheap Chinese equipment in situations where people had a new laptop and an old mouse ( different Bluetooth release level) and then they added something like a printer or card reader that used the USB 3.0 port.

So manufacturers started working on the problem. Some of them just stopped putting USB 3.0 ports In. Some reoriented the internal antennas. Most better quality devices added shielding. (All noted in the PCMag article that Ron linked to.)

And IT techs learned how to troubleshoot The problem and work around it as much as possible:

But you still run into it every once in a while, especially when devices are too close together.

(Dan P Parker) #19

I wish I’d seen this thread a couple weeks ago. That’s when I added a USB 3.0 hub to my PC setup, with the new gizmo sitting less than 1 ft from my ST hub, and shortly before I had all of my Zigbee devices start flaking out on me occasionally, but always all at the same time. This went on for several days, and I had myself convinced that the ST Zigbee radio was exhibiting some sort of intermittent failure all of a sudden. But then I noticed that the failures always occurred (or I noticed them) either while or shortly after I had the PC…and therefore the USB hub…powered on. A quick Google search turned up multiple papers that warned about the issue, including the one linked previously. I simply relocated the ST hub a few feet away and that immediately eliminated the problem.


Thanks a lot guys, now I absolutely have to try this out for myself!

rummages through cable drawer