Question Network speed reduced to 100 mbps after 4 years of correctly working on 1 Gbps

[WimP]

I'm using a Realtec PCIe GbE Family network adaptor on a Lenovo V320-17IKB laptop running Windows 10 Pro Version 22H2 Build 19045.3570.
In the exact same hardware configuration it has run on 1 Gbps for about 4 years until three weeks ago, where, after the reconnect, it's network speed appeared to be reduced to 100 Mbps.
I use this laptop on a dedicated place, interrupted (for probably over 1000 times) by use elsewhere.

In the last 3 weeks, I have tried a dozen cables, (Cat5e or Cat6) other than the original, (which ran on 1 Gbps for about 4 years) all with the same result of 100 Mbps.
All those cables (including the original one) run flawlessly at 1 Gbps on all other devices I've tried them on.
The Realtec diagnostic tool indicates all 4 pairs at the correct length for each cable (3m, 5m, 10m and 20m respectively).
I've tried the different parameters in the network settings that may influence the 1 Gbps in all the possible combinations (64 possible combinations, on or off, in total) all with the same (non-) result of 100mbps.

What's my next step?

 

[Lutfij]

Welcome to the forums, newcomer!

I'd first try and see if your laptop is pending any BIOS updates, then see if the OS is pending any updates, then finally try and remove your NIC's drivers, then manually reinstall with the latest sourced off of Lenovo's support site.

If one end of your Ethernet cable terminates at the laptop, where does the other end terminate to?

 

[WimP]

BIOS, Windows, SW and HW drivers all appear to be up to date, I already reinstalled the drivers on the first day of 100 Mbps restriction, rebooting the machine enough times in between to be sure no residual parts of previous instances remained.
The other end of the cable goes into a 1Gbps switch as it has been in the past 4 years (or up to 6 years for the other machines). I already tried swapping switch ports, the problem stays with the Lenovo laptop, independent of the used switch port.

 

[bill001g]

The speed on a ethernet port is negotiated electrically in hardware. It is not really a driver/firmware thing other than you can force it to 100m max. In 99% of the cases it is a ethernet cable issue and lately is worse because of all the fake cable sold.
Make sure the cable you are trying are pure copper wire with wire size 22-24. Those flat cables have wires much too thin if you are trying those.
After this you start to suspect the port itself and on a laptop you can't just stick in a new PCIE card and you need a USB3 port to use a USB adapter.
I guess you really verify that it is not software by booting a linux USB image but ethernet speed is a almost all burned into the chips.

 

[WimP]

The used cable has been working correctly at 1 Gbps on that Lenovo RJ45 port for 4 years, so nothing changed there. I've not enough experience in linux to install a system from an untrustworthy situation, so it will probably come to buy and try using a USB3 - 1Gbps network interface.

 

[kanewolf]

I'm using a Realtec PCIe GbE Family network adaptor on a Lenovo V320-17IKB laptop running Windows 10 Pro Version 22H2 Build 19045.3570.
In the exact same hardware configuration it has run on 1 Gbps for about 4 years until three weeks ago, where, after the reconnect, it's network speed appeared to be reduced to 100 Mbps.
I use this laptop on a dedicated place, interrupted (for probably over 1000 times) by use elsewhere.

In the last 3 weeks, I have tried a dozen cables, (Cat5e or Cat6) other than the original, (which ran on 1 Gbps for about 4 years) all with the same result of 100 Mbps.
All those cables (including the original one) run flawlessly at 1 Gbps on all other devices I've tried them on.
The Realtec diagnostic tool indicates all 4 pairs at the correct length for each cable (3m, 5m, 10m and 20m respectively).
I've tried the different parameters in the network settings that may influence the 1 Gbps in all the possible combinations (64 possible combinations, on or off, in total) all with the same (non-) result of 100mbps.

What's my next step?

One possibility is that you bent one of the eight pins in the ethernet port with those 1000 connections. Visually verify that there are 8 parallel wires that are all the same height in the ethernet port on the laptop.

 

[WimP]

Already checked that out, and the Realtec diagnostics on the Lenovo shows me correct connections of the correct length on each of the 4 pairs on each of the tested cables.

 

[bill001g]

If you a sure it is not the cable then you need to find a way to not use the port on laptop motherboard.

 

[kanewolf]

Already checked that out, and the Realtec diagnostics on the Lenovo shows me correct connections of the correct length on each of the 4 pairs on each of the tested cables.

Have you tried connecting the laptop to any other wired network hardware? Does it EVER give a 1Gb link?
Do the LEDs on the router/switch show 100Mbit link speed ?

 

[WimP]

It has given a 1Gbps link for the past 4 years, up until 3 weeks ago. I only have one 1 Gbps switch in the building, of which I have tried several different ports.
Tomorrow I'l probably have a USB3 - 1Gbps ethernet adapter, which i will try next.
The switch shows no difference between the Lenovo and the other devices, (all LED's are equally green) though all other devices demonstrate a 1 Gbps connection (110 MBps) between eachother and a 100 Mbps connection (11 MBps) to the Lenovo.

 

[kanewolf]

It has given a 1Gbps link for the past 4 years, up until 3 weeks ago. I only have one 1 Gbps switch in the building, of which I have tried several different ports.
Tomorrow I'l probably have a USB3 - 1Gbps ethernet adapter, which i will try next.
The switch shows no difference between the Lenovo and the other devices, (all LED's are equally green) though all other devices demonstrate a 1 Gbps connection (110 MBps) between eachother and a 100 Mbps connection (11 MBps) to the Lenovo.

So, with that last statement, have you not verified that Windows actually shows a 100Mb link rate for the ethernet port ?

 

[WimP]

When I move some files from or to the Lenovo from another computer, both indicate a data rate of 11 MBps, (100 Mbps), but on the Lenovo that is shown as 100 % of 100 Mbps network usage and on the other computer it is shown as 10 % of 1 Gbps network usage in either direction. If I move some files between two other computers both get a transfer of 1 Gbps at 100 % network usage. Up until three weeks ago, the Lenovo also showed 110 MBps at 100 % of 1Gbps and transferred a file of 330 MB in about 3 seconds instead of the current 30 seconds.

 

[WimP]

The new 'USB3' adapter appears to be USB2, i see a 1Gbps network card that seems to be restricted to about 35 MBps instead of 110 MBps. It shows 35 % of 1 Gbps usage.
Trying to copy to a ssd hdu through the USB3 HUB part of the device restricts to the same speed (35 MBps), while a direct connection of the HDU (to the same USB port as was previously used by the network adapter) shows me 330 MBps transfer. And I'm using the same cable as before, now with 1Gbps connection to the same hardware, so I suspect the RJ45 connection on the Lenovo is the culprit.

 

[bill001g]

There should be a device information page that shows what windows thinks the end device is running. It should show you if it thinks the device is only USB2 even when it is plugged into a USB3 port.

Network hardware seem to not like you much lately with 2 devices not wanting to work properly. Key though is you are now getting more than 100mbps which means your cables and everything else in the path now is working properly.

I have a USB3 ethernet nic and it will test over 900mbps even though it does seem to have random packet loss issue when I am running high cpu load applications.