Realtek ethernet adapter refusing to be/stay on Gigabit

Laith · 02 Jul 2020

Hey TenForums, long time no see!

Basically, I've been having this weird issue for the past couple of days that has driven me to the point where I'm almost pulling my hair out. The issue is that my Realtek network adapter (the RTL8111H) will not stay, or even be on gigabit speeds. I have no idea what's causing this because the RTL8111H and router are both CAT5e, and the cable is a brand new CAT6 one.

I've spent countless hours trying to debug this by messing around with the duplex settings with almost no success. Even though that's case, I actually did "succeed" during two occasions.

During the first, I got gigabit running for around 10 seconds, until it disconnected and went back to 100Mbps.

During the second, I had a much bigger success where I was able to get gigabit running until I restarted my machine. What I did then was to try other cables to see if my CAT6 was faulty and they did indeed give me gigabit speeds. I decided after that to plug in my CAT6 one and to my surprise it worked perfectly, until I rebooted that is.

It is worth mentioning that Auto Disable Gigabit, Gigabit Lite, EEE/Advanced EEE and Green Ethernet are all turned off. Duplex is set to 1.0Gbps Full and I'm running the latest drivers from my motherboard manufacturers website.

This has been really frustrating for me since I just got a network upgrade and I'm only getting 1/4 of the speed and on top of that, I have no idea what the culprit can be. I thank you for any replies in advance!

Compumind · 02 Jul 2020

@Laith -

Please tell me something.

Are you connecting the computer to your cable/fiber modem directly via ethernet cable or to a discrete router?
If it is a discrete router, go from the computer directly to the cable/fiber modem and test again after a reboot.

Post back. Thanks.

Samuria · 02 Jul 2020

Most often its down to setting full duplex as most home routers cant cope as it sends and recieves at the same time

Laith · 02 Jul 2020

Compumind said:

@Laith -

Please tell me something.

Are you connecting the computer to your cable/fiber modem directly via ethernet cable or to a discrete router?
If it is a discrete router, go from the computer directly to the cable/fiber modem and test again after a reboot.

Post back. Thanks.

Samuria said:

Most often its down to setting full duplex as most home routers cant cope as it sends and recieves at the same time

Hi and thank you for your responses! I forgot to mention in the original post that I'm connected directly to my router and my router is connected to fiber using a coax connection. This is done partly because of making things proprietary to the biggest ISP in Sweden. As for the duplex settings, it is set to 1.0Gbps Full, as mentioned in the original post. The router, when I had gigabit, picked it up as full gigabit in it's configuration and gave me the appropriate speeds.

Compumind · 02 Jul 2020

Hi.

Could be a problem with Ethernet Auto-Negotiation.

Make sure that both sides of the internet link are configured the same way.

If one side of the link is set to auto-negotiation, make sure the other side is also set to auto-negotiation.
If one side is set to 1000 / full duplex, make sure the other side is also set to 1000 /full duplex.

Gigabit Ethernet should always be set to auto-negotiation, unless there is a compelling reason to do so (such as an interface that will not properly negotiate).

So your modem and router are combined?

Compumind · 02 Jul 2020

With Powershell run the following for your Realtek:

> Get-NetAdapter | SELECT name, LinkSpeed, fullduplex | ft -autosize

Post back with the results - screenshot.

Thanks.

Laith · 02 Jul 2020

Yes, the router is a router + modem combined.

I've set the duplex to autonegotation due to the router having it at that. This is the result from the powershell command:

Code:

name         LinkSpeed fullduplex
----         --------- ----------
Ethernet     100 Mbps        True

Compumind · 02 Jul 2020

Why only 100 Mbps?

Are you sure that this NIC supports 1 Gbps?

Now turn off the modem/router, and computer (shutdown.)
Then restart modem/router - let initialize fully. Then restart the computer.

Please do this -

1. Click on Network and Internet Settings.
2. Once inside, click on Ethernet.
3. Click on Change adapter options.
4. You need to set the network cards on the computer. Double click on Ethernet. You see that it tells the speed within the information.
They can be 100 Mbps or 1 Gbps. If it is the second, everything is fine, but if it is the first one, you have to configure it.

Here's how to configure it to 1 Gbps. The steps to follow are these:

1. In the window where the speed was indicated, click on properties.
2. Make sure that the Microsoft Network Client option is checked.
3. Now click on configure.
4. Next, go to advanced options and look for Speed & Duplex.
5. We have to change the value by 1.0 Gbps, Full Duplex.
6. Press accept.

Reboot the computer and test.

Ok?

(Revised.)

Laith · 02 Jul 2020

Compumind said:

Why only 100 Mbps?

Are you sure that this NIC supports 1 Gbps?

Now turn off the modem/router, and computer (shutdown.)
Then restart modem/router - let initialize fully. Then restart the computer.

After you login, test your throughput and post back.

Ok?

According to their website, yes, it is CAT5e and supports gigabit speeds. As said in the original thread, I've had success twice running at this speed.

I tried restarting the router and computer in the way you told me to with no success.

Compumind · 02 Jul 2020

See revised post above.