I am seeing baffling behavior with my wireless mouse (connected via USB) and my gigabit ethernet adapter plugged in simultaneously.

If my mouse is plugged in and working fine, if I plug in my gigabit ethernet adapter (even without the ethernet port plugged in) to EITHER thunderbolt port, my Logitech m510 mouse stops working completely.

I have plugged in my external monitor to both thunderbolt ports, and it doesn't affect my mouse at all. What the hell is going on here?

5 Answers 5


The reason you are seeing the symptoms present when you connect an ethernet adapter to the TB port and not when you connect a monitor to the TB port has to do with what is being passed over the TB cable.

TB multiplexes at least 2 signals over the same connection. In this case, video and PCIe. Yes, basically the same PCIe bus that you would find looking inside any computer is now on that cable.

Thunderbolt Technology Brief

So, basically speaking, when you are connecting the DP to TB, you only get video. When you connect the ethernet adapter, you are connecting to PCIe. When you daisy chain devices, you get both.

Your mouse stops working because the ethernet adapter is generating noise that is interfering with your receiver. It is the PCIe "signals" that is creating this noise within the ethernet adapter. It is not interfering with the USB port - just the wireless radio reception/transmission of the receiver. I know this for a fact because:

1) I experienced it myself. I have a Logitech Anywhere MX (non bluetooth) and bought a TB to Ethernet adapter. I had the same issue. I changed out my TB to Ethernet adapter to a more reputable brand and the problem went away.

2) I found this answer on Logitech support forum

3) Plug in a USB hard drive. If it was interfering with the USB, the hard drive would fail as your mouse does.

The reason that when you move it from one port to another it "sorta" works is because you have lessened the wireless interference, not eliminated it.

Here is the Apple Ethernet adapter that I bought that solved my issue.

If you want to confirm this, buy a USB extension cable to move your unifying receiver to another location (sometimes logitech includes this with their mouse). Or, plug in the unifying receiver into a hub away from the ethernet adapter. The problem should go away.

  • 2
    I've had the same problems even with the Apple Ethernet adapter. The USB extension seems to work. May 5, 2016 at 12:48

Well I swapped the USB receiver for the mouse to the other usb port and it seems to be working now but pretty erratically.


I had a similar problem with a Logitech wireless mouse. I "fixed" it by relocating the mouse dongle. For some reason, when the ethernet cable is plugged in near the adjacent USB port, the mouse gets jittery, sluggish or even freezes. Simply moving the mouse receiver to the front of the case solved the issue, but I really have no idea why the ethernet cable should interfere with the mouse signal.

Dell Optiplex 755 (refurbished SFF) Windows 7 Pro 64 bit


Try connecting a shielded/braided USB cable between the USB dongle and the USB port. This type of problem is often caused by electrical noise between the ports (generated by USB 3 or thunderbolt circuitry), using a shielded cable helps to absorb the high frequencies.

  • There is no noise between the USB ports. The noise is is coming from the Ethernet adapter itself which is interfering with the 2.4GHz signal the mouse uses to communicate. If there was "noise between the ports" then a wired mouse would fail just as a wireless one does.
    – Allan
    Feb 11, 2016 at 2:16

The problem has nothing to do with the mouse's nano USB receiver or the Thunderbolt Ethernet adaptor, and everything to do with the Thunderbolt port next to the USB port.

If you are running Windows on your Mac the Thunderbolt ports are not plug-and-play therefore you can plug a device into the Thunderbolt port and the mouse still works fine, however once you re-boot Windows with a Thunderbolt device, such as the Ethernet adaptor, plugged in and the device is recognized and the Thunderbolt port opened. Even if you "hot" unplug the device the Thunderbolt port stays open and continues to cause the problem

If you move the mouse within 1 inch of the USB receiver it works, but if it is further away it seem the open Thunderbolt port causes a problem, perhaps distorts the 2.4GHz signal from the mouse, or maybe the motherboard and Thunderbolt and USB ports are not well grounded from Apple.

The exact same problems occur even if you are running Apple OS-X Y, the only difference is that the Thunderbolt ports are plug and play therefore the problem is continuous from the time you boot the system no matter whether a Thunderbolt device is plugged in or not.

If you disable the Thunderbolt ports in Windows and OS-X Y there is no problem.

The question is: is this an isolated problem with just USB Nano receivers, or does the Thunderbolt port cause a problem for any USB device plugged in? If it does, this is a serious design problem because that would mean that a USB hard drive will cease to operate correctly while the Thunderbolt ports are open.

Yes, moving the USB device to the other side of the laptop computer also solves the problem, but that limits the use of all the ports which we paid for.

Macs were nenver designed to use USB Nano mouse receivers. They were designed to use the Apple mouse which I think is Bluetooth.

  • Most of this answer makes zero sense. If the Thunderbolt port was causing interference (not "distortion") with the wireless mouse's signal, it would do so when the monitor was plugged in, too, not just the ethernet adapter.
    – tubedogg
    Jun 8, 2015 at 3:32
  • This answer is fundamentally incorrect as to the technology of Thunderbolt, its uses/functions, USB in general, Apple's manufacturing process and how it all relates to WiFi and USB connectivity. I suggest getting a primmer on how Thunderbolt works from the folks who developed it; Intel Corp.
    – Allan
    Jun 14, 2015 at 13:30

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