# Wired network speed capped after fresh Windows 10 installation



## btarunr (Mar 10, 2018)

Strange issue with the wife's PC.

After a fresh Windows 10 OS installation, the wired networking interface refuses to go above 10 Mbps. The only time it will go above 10 Mbps is when I'm running Speedtest.net . It will then max out my 300 Mbps connection. Otherwise, no app whatsoever is able to move any data above 10 Mbps.

The NIC is a crappy RTL8111H. It's plugged into the router via a 1 GbE-capable cable (as I said, Speedtest.net somehow crosses that 10 Mbps limit, and Task Manager confirms that).

I've tried:

1. Updating NIC drivers
2. Forcing "1 Gbps Full-duplex" in NIC settings (as opposed to auto-neg).
3. I've not hit the FUP limit of my ISP (I'm 735 GB away from hitting it).

Halp


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## jboydgolfer (Mar 10, 2018)

Really weird


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## Boatvan (Mar 10, 2018)

I'm a network noob (working on my CCNA), but I think if auto-negotiation fails, the default speed is 10 half-duplex. At least for Cisco devices... Forcing 1 Gbps full on the PC should have worked if the router port was trying to go 1 gbps full. Perhaps log into the router and look at the port she's plugged into?


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## btarunr (Mar 10, 2018)

Boatvan said:


> I'm a network noob (working on my CCNA), but I think if auto-negotiation fails, the default speed is 10 half-duplex. At least for Cisco devices... Forcing 1 Gbps full on the PC should have worked if the router port was trying to go 1 gbps full. Perhaps log into the router and look at the port she's plugged into?



Router says 1 Gbps. I've also tried plugging this into different downstream ports of the router, as well as directly plugging the fiber switch. No luck. I've never heard of anything like this.


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## Boatvan (Mar 10, 2018)

btarunr said:


> Router says 1 Gbps. I've also tried plugging this into different downstream ports of the router, as well as directly plugging the fiber switch. No luck. I've never heard of anything like this.


Super weird. It does now sound like the issue is the PC unless there is suddenly a cabling issue, which would be a huge coincidence. What driver version are you on now?

EDIT: On realtek's site, there is a driver that was released about a week ago. (10.0.25). I am assuming this is the driver you updated to?

Sorry for double posting, but this may be relevant? Feel free to merge the posts, I just want you to see this.

https://www.ghacks.net/2016/08/05/windows-10-limiting-internet-speed/


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## jboydgolfer (Mar 10, 2018)

I know you said that the problem doesn't show up when you run speed tests, but is there a chance of  some type of bandwidth policy , or application prioritization, or QOS setting that has been enabled by default or by accident?  I realize that it wouldnt be just a single device doing it ,but I really can't think of what the heck would cause this, and I'm trying to think of what I would do if I was in your position. resetting the router to factory default would be one of them ,as well as power cycling both the modem and router ( even though it's a shot in the dark).  Super strange

have you tried setting your windows adapter link speed to "auto" ? instead of full duplex, or whatever other manual options there is?

maybe try to run elevated CMD prompt:
check auto tune setting? *netsh interface tcp show global*.
Locate the "Receive Window Auto-Tuning Level" value under TCP Global Parameters. If it is not set to disabled, it is being used by Windows to optimize TCP connections.

or try disabling auto tune to see if it helps with.  *netsh int tcp set global autotuninglevel=disabled*
if that isnt the issue, you can enable it again with. *netsh int tcp set global autotuninglevel=normal*


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## Deleted member 67555 (Mar 10, 2018)

I just had an issue very similar..
I had to deauthorize the known devices on the network, refresh and start anew.


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## Aquinus (Mar 10, 2018)

It might be reducing the link speed when the driver thinks the interface is idle. I would disable power saving features on the network device and see where it gets you. I suspect there might even be a setting to disable this behavior.


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## Bill_Bright (Mar 10, 2018)

This is really odd since nothing should be discriminating between programs. While Speedtest is designed to test your maximum bandwidth, the fact it can hit that 300Mbs speed tells me Windows and your computer hardware and your network are working properly. 

Got another computer you can try?


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## btarunr (Mar 10, 2018)

jboydgolfer said:


> I know you said that the problem doesn't show up when you run speed tests, but is there a chance of  some type of bandwidth policy , or application prioritization, or QOS setting that has been enabled by default or by accident?  I realize that it wouldnt be just a single device doing it ,but I really can't think of what the heck would cause this, and I'm trying to think of what I would do if I was in your position. resetting the router to factory default would be one of them ,as well as power cycling both the modem and router ( even though it's a shot in the dark).  Super strange
> 
> have you tried setting your windows adapter link speed to "auto" ? instead of full duplex, or whatever other manual options there is?
> 
> ...



That auto-tuning thingie was "normal" and I disabled it. Performance is still throttled.



Bill_Bright said:


> This is really odd since nothing should be discriminating between programs. While Speedtest is designed to test your maximum bandwidth, the fact it can hit that 300Mbs speed tells me Windows and your computer hardware and your network are working properly.
> 
> Got another computer you can try?


All other devices connected to this network work normally. The main rig does 300 Mbps just fine.

Problem solved. I pulled out an Intel Gigabit CT PCIe NIC from the dungeon and installed it. Speeds back to normal.


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## Bill_Bright (Mar 10, 2018)

That still does not make sense. I suspect if you go back to the Realtek, it will work right now as whatever setting was off has been reset.


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## Jetster (Mar 10, 2018)

Turn off QoS and see what happens. I've had this issues and that fixed it


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## btarunr (Mar 11, 2018)

Bill_Bright said:


> That still does not make sense. I suspect if you go back to the Realtek, it will work right now as whatever setting was off has been reset.



You're absolutely correct. RTL speeds are back to normal now. Very strange.


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## qubit (Mar 11, 2018)

btarunr said:


> Problem solved. I pulled out an Intel Gigabit CT PCIe NIC from the dungeon and installed it. Speeds back to normal.


That's great.

However, if you're still up for troubleshooting the original NIC, then I wonder, what drivers did you update to? Were they just from Windows Update? They are often not the best drivers in my experience. Try getting the drivers from the NIC manufacturer's website and see how it goes. What about trying the drivers from the original CD if you have one?

Also, check QoS as Jester suggested and see if there are any settings in your firewall/security software that could be throttling it depending on content. Perhaps there's a Group Policy setting somewhere too, although I doubt this one.


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## btarunr (Mar 11, 2018)

qubit said:


> However, if you're still up for troubleshooting the original NIC, then I wonder, what drivers did you update to? Were they just from Windows Update? They are often not the best drivers in my experience. Try getting the drivers from the NIC manufacturer's website and see how it goes. What about trying the drivers from the original CD if you have one?
> 
> Also, check QoS as Jester suggested and see if there are any settings in your firewall/security software that could be throttling it depending on content. Perhaps there's a Group Policy setting somewhere too, although I doubt this one.



I always try to keep non-GPU drivers as Microsoft as possible. So I first used whatever drivers Windows gave me. Those annoying millennial-safe "We're updating, please don't unplug or it will mess things up (sic)" messages during Windows setup went on for a hour. I knew something was off. After first noticing the capped bandwidth, I installed the latest drivers from Realtek drivers and turned off every feature that remotely relates to energy-efficiency. I then popped in the Intel NIC and speeds were back to normal. I reverted back to the Realtek onboard LAN, and speeds were normal there, too. Gremlins.


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## qubit (Mar 11, 2018)

That's a weird one. Perhaps there's a BIOS issue or something. At least the quick fix worked.


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## Hockster (Mar 11, 2018)

Wait, you use something besides Intel NIC's?


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## btarunr (Mar 12, 2018)

Hockster said:


> Wait, you use something besides Intel NIC's?



I use Intel NICs, my wife doesn't care (it's her build). I could add this Gigabit CT PCIe, but then again, I could leave it in the dungeon for future troubleshooting.

The "Your PC ATM" thread has pics of this build.


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## Hockster (Mar 12, 2018)

I just despise anything from Realtek.


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## Bill_Bright (Mar 12, 2018)

Unless a company make just one product that has a horrible reputation, I think it's a shame to dismiss all the products from a company - especially when the company makes many and a wide variety of products.  Holding such grudges based on biases and prejudicial beliefs due to bad experiences in the past with one or two products creates missed opportunities to experience quality products from the company. 

The fact of the matter is, Realtek makes great stuff. Have some people experienced problems? Of course! Until Man can create perfection 100% of the time, there will be problems. But most people never have problems with their Realtek products - including with Realtek NICs.


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## Hockster (Mar 12, 2018)

Thanks Bill for completely over-explaining something that needed no explanation at all.


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