Advanced IP diagnostic with Windows 11

Hi all,

My laptop is wired to my main home Ethernet and it's been on the slow side for a while. I blamed the TARGUS dock I had but it does the same with a USB dongle.

If I transfer a big file from my laptop to my main desktop, sometimes I have full bandwidth (1Gbit/s), sometimes it slows down to 7/800Mbit/s and sometimes even lower to 400Mbit/s.
I have tried disconnecting everything BUT the laptop and I don't see improvements.

HOWEVER, if I restart the switch on that end of the network, then I get constant 110MB/s.

So, something is not working as expected.
- My Laptop (unlikely as I tried Ethernet via a dock and via a USB dongle)
- The Switch
- The wiring (it's a long-ish cable running outdoor but <30m)
- Something within the network which causes havoc

As a first step I'd like to see if the adaptor is reporting transmission errors: I remember Intel adaptors had a diagnostic page to check that, is that something under W11 that can be opened to check, or any software you'd recommend?

Assuming it's a wiring issue, if the signal is noisy, would an Ethernet adaptor drop its speed to something like 800 or 400Mbit/s? Or would I just be an erratic speed?

Thanks for any ideas!

Interesting issue - I may have an idea what is happening, but I cannot be sure that this is it.

By any chance do your Targus dock and the USB Ethernet adapter have USB-C connectors? If not, you can ignore what follows.

I have several USB-C Ethernet adapters and I was getting inconsistent results with them. I have since then discovered that these adapters are not wired with full "bi-directional" connections. Put another way, plug in the adapter in one direction and you get full USB 3 speed to the adapter. Rotate the connector 180 degrees and you get only 480 Mbps (USB 2 speed) to the device. Some other devices such as USB-C to USB-A adapters also have the same issue. You will note that some such adapters specifically note in their advertising that they are "bi-directional" (or they might use other similar terms). Those adapters will give you the full speed no matter which direction you plug in the device into the USB-C connector.

I stumbled upon purely by accident as I was trying to troubleshoot my USB-C based Ethernet adapters when I was getting inconsistent results.

The Targus is USB-C but the direction is fixed - the plug which goes on the dock has screws.
The Ethernet on the Targus is integrated. The ones I've been testing (a Lenovo one and an AmazonBasic) are both USB-A.

I didn't realise the 400Mbit to be close to the 480Mbit/s USB-2 offers. Interesting thanks.
I wish Windows had a better way to diagnose those things, showing actual link speeds between USB peripherals.

it looks like I have a number of faults on this line.

The Dock seems to have issues with its own Ethernet port.
One of the switches on the line is definitely having issues (it drops the connection sometimes)
The long line I ran externally seems to be noisy

I bypassed everything with a 15m long pre-made, shielded cable and a USB-Ethernet dongle and the speed line under Task Manager is a ruler at 113MB/s.
If I use the existing Ethernet line I ran, it's not so flat which suggests noise I guess. Though if I remove the dodgy switch and the Dock from the equation it's reasonably flat and stays around 105/110MB/s

I think I'll try to remove a couple of joints I have on that line (made with cat6 punch couplers, nothing nasty) and worst case scenario I might need to replace that cable with a better one - this is unshielded, it was the only one I could find locally suitable for outdoor.