1Gb being capped at 100Mb

[Senbotsu]

So this is a bit of a stumper for me.  For some reason this PCs connection is being throttled to 100Mbps even though every test I can run says the port is running properly at 1 gigabit, full duplex.  Both a LAN data transfer and a WAN speed test choke out around 104-ish Mbps.  I've replaced cables, completely removed and done a clean reinstall of drivers, checked bios settings (and updated bios), and tested the adapter itself for mechanical issues.  All the other PCs on the network can transfer at 900-1000Mbps both cross-network and internet speed tests.

 

- a Klein port tester reports no problems with the port or SNR issues with the ethernet cables.

- adapter status within windows says it's running at 1 Gbps as well:

 

 

[sphbecker]

What kind of adapter is it? Are you statically setting the speed or duplex on the switch port? If so, you should leave them to auto for client use.

[Senbotsu]

I left it on auto (after forcing it made no change)

 

Edit: never responded to the adapter question, sorry.  It's the Intel I219-V integrated adapter that comes with the Asus ROG Maximus Hero XI motherboard.

[cole0622]

Are you sure the pc is not the bottleneck

[Senbotsu]

If you mean the hardware, quite sure.  Especially since I was getting gigabit speeds a few days ago, went to bed, and the next day crap internet.  After much hoop-jumping I isolated it to this PC, and I'm assuming at this point that it has to be something windows/software related but short of giving up and doing a clean install (which I don't really want to do) I'm at a loss.

 

[cole0622]

I would check in task manager or resourse monitor to see if any resources are being heavily used. Also quote me so I know you have responded.

[Senbotsu]

20 minutes ago, cole0622 said:

I would check in task manager or resourse monitor to see if any resources are being heavily used. Also quote me so I know you have responded.

No particularly high resource usage: 

[cole0622]

3 minutes ago, Senbotsu said:

No particularly high resource usage: 

did you recently get an update?

[Senbotsu]

2 minutes ago, cole0622 said:

did you recently get an update?

Checking the update log, the last system update was on the 30th of last month.. so ~10 days ago.  I don't *think* it's the root cause, but I've lost track of how many days I've been trying to fix this issue, lol.

[cole0622]

4 minutes ago, Senbotsu said:

Checking the update log, the last system update was on the 30th of last month.. so ~10 days ago.  I don't *think* it's the root cause, but I've lost track of how many days I've been trying to fix this issue, lol.

you might do another speed test and watch the adapter to see if it is reaching 100% utilization

[Senbotsu]

14 minutes ago, cole0622 said:

you might do another speed test and watch the adapter to see if it is reaching 100% utilization

11% util:

 

And if I run the same speedtest from a different computer plugged into the same port of the router using the same cable: 

 

[Senbotsu]

So at this point, either there is something wrong with the adapter that I can't detect with testing equipment (which is possible, I've seen it happen before but it's super rare) or something has gone amiss with windows and it's decided to poop itself.  I think my next step at this point is to do a dual boot to either verify or eliminate software as the issue.

[cole0622]

I would boot off of a usb drive and see what happens, additionally there could be interference being picked up by the network cable.

[Senbotsu]

9 hours ago, cole0622 said:

I would boot off of a usb drive and see what happens, additionally there could be interference being picked up by the network cable.

Ok, having made a boot USB with Kubuntu 19.10 and booted to that, it's definitely windows being a jerk.  The speed test was over 900Mbps when ran in kubuntu:

[Senbotsu]

Ok, so in a last ditch effort to revert whatever windows broke without just re-installing windows, I ran a TCP optimizer that tweaked a bunch of windows settings and that seems to have fixed it for now.

[cole0622]

awesome glad you found a fix