Differing Internet Speeds for Wired Devices

[rmiller1959]

We just had a 300 mbps Internet service installed in our home, and my desktop routinely registers average speeds of 315 mbps. Needless to say, I'm very pleased.

My wife and son, however, have their desktops connected to the same router via Cat 6A Ethernet cables, as I do, and their average speeds are 1/3 of mine. I disconnected their desktops and plugged their cables into a laptop to do some troubleshooting, and the laptop achieves over 300 mbps, so I know the cables aren't the cause.

Is it possible that their integrated NICs are not as capable? They both claim to be gigabit Ethernet NICs, and RealTek is the manufacturer for all the desktop NICs in use in our household. I'm trying to eliminate all options before I simply revert to upgrading their motherboards or buying a standalone NIC if they still make such a thing. I'd appreciate your help!

 

[ColinTaylor]

1/3 of 300Mbps is suspiciously like 100Mbps. So I'd check that the negotiated link speed as reported by the adaptor is actually 1000Mbps and not 100Mbps.

 

[rmiller1959]

I'll double-check. I think it's set to auto-negotiate, but I'll confirm.

 

[ColinTaylor]

I'll double-check. I think it's set to auto-negotiate, but I'll confirm.

Auto-negotiate is the correct setting but the actual negotiated speed can be checked on the network adaptor's status panel.

 

[rmiller1959]

Here is the information I was able to glean from the network status page:

Name: Ethernet 2
Description: Realtek PCIe GbE Family Controller #2
Physical address (MAC): 30:5a:3a:48:9d:4e
Status: Operational
Maximum transmission unit: 9198
Link speed (Receive/Transmit): 1000/1000 (Mbps)
DHCP enabled: Yes
DHCP servers: 192.168.1.1
DHCP lease obtained: ‎Saturday, ‎March ‎23, ‎2019 9:40:12 AM
DHCP lease expires: ‎Sunday, ‎March ‎24, ‎2019 9:40:12 AM
IPv4 address: 192.168.1.3/24
IPv6 address: fe80::f0a4:3daf:445a:32a9%9/64
Default gateway: 192.168.1.1
DNS servers: 192.168.1.1
DNS domain name:
DNS connection suffix:
DNS search suffix list:
Network name: Network 5
Network category: Public
Connectivity (IPv4/IPv6): Connected to Internet / Connected to unknown network

Here is the Speedtest result for this desktop:

And here is the Speedtest result for a laptop with a Qualcomm Atheros gigabit ethernet adapter:

Does this reveal anything to anyone?

 

[ColinTaylor]

I can't see the images yet (I guess they'll appear shortly), but there's nothing strikingly wrong with the status information.

There are a couple of things that's a bit unusual;

1) The Network category is Public when is should be Private if this is a home computer.

2) The Maximum transmission unit is 9198 which is unusual because it means the network adaptor is trying to use Jumbo frames. Unless everything else is using Jumbo frames that will result in packet fragmentation and an associated performance drop. Try disabling Jumbo frames.

 

[rmiller1959]

Apologies for the inability to see the images. Here is the data:

Desktop Speedtest: 107.73 mbps download, 9.54 mbps upload
Laptop Speedtest: 321.79 mbps download, 12.93 mbps upload

I made the adjustments you recommended; as soon as my wife allows me to reboot her machine, I'll see if disabling jumbo frames made a difference. FWIW, my desktop is set to the "Private" network category and jumbo frames are disabled.

 

[coxhaus]

I bet the jumbo frames is at the root of the problem. Good call Colin Taylor. Jumbo frames not setup correctly will cause a lot of fragmentation on the network.

Jumbo frames are not worth it my opinion.

 

[rmiller1959]

Apologies for the inability to see the images. Here is the data:

Desktop Speedtest: 107.73 mbps download, 9.54 mbps upload
Laptop Speedtest: 321.79 mbps download, 12.93 mbps upload

I made the adjustments you recommended; as soon as my wife allows me to reboot her machine, I'll see if disabling jumbo frames made a difference. FWIW, my desktop is set to the "Private" network category and jumbo frames are disabled.

I rebooted and ran Speedtest again, with the same result. I changed the speed and duplex setting from "auto-negotiate" to "1.0 Gbps Full Duplex" and rebooted. Same result.

I'm not sure what the next step would be. I welcome your advice!

 

[degrub]

Just some additional ideas....looking for pattern differences....

For Gb link rate there usually are two lights on at each lan interface.
Gb link rate does not mean Gb throughput usually.

What OS is being used in each of the machines ? All same ? All 64 bit ?

Is the NIC in each the same Realtek chip ?
Same MB chipset ?
Are the drivers for both at the same revision number across devices (if common) ?

MB bios version ?

What MTU is being used in the router ? Jumbo Frames enabled ?
If so, it needs to match across all the devices. MTU=~1500 (i forget the exact number) is common.

Just for grins, have you shutdown all of the devices, rebooted the router, and then re-started the devices ?

 

[rmiller1959]

Let me see if I can address your questions.

• There are two lights on at each LAN interface, a green stable light and an amber blinking light
• All the machines are using Windows 10 64-bit (one is Pro, the rest are Home)
• The MB chipsets/LAN Controllers/(Download/Upload speed in mbps) are:

• • Intel z170/Realtek® RTL8111H, 1 x Gigabit LAN Controller (319.90/21.43)
  • AMD A88X/Realtek® RTL8111GR, 1 x Gigabit LAN Controller (106.29/8.01)
  • Intel Z77 Express/Intel 82579V Gigabit LAN Controller (317.29/18.45)
  • Intel HM77/Qualcomm Atheros AR8151 PCI-E Gigabit Ethernet Controller (318.04/18.86)
• The latest drivers for all LAN controllers are installed and the BIOS is the latest available for each motherboard
• Jumbo frames are disabled
• Reboots have been tried multiple times

Note that the speed on the Intel HM77/Qualcomm system, a laptop, is 318.04 mbps download, 18.86 mbps upload, when connected to the router USING THE SAME CABLE as the one connected to the AMD/Realtek desktop that is performing at 1/3 of the speed (106.29 mbps download, 8.01 mpbs upload). That is why I've eliminated the cable, router and cable modem as potential culprits.

Ethernet cables are all Cat 6A. The router is a Netgear Orbi RBR50, and the cable modem is an ARRIS Touchstone DG3450 DOCSIS 3.1 Cable Gateway in bridge mode.

 

[degrub]

Well, the one thing that stands out to me is the AMD chipset versus all the other Intel chipsets.
You could try an Intel nic in that mb, but i would do some research on the mb manufacturer’s support site first, maybe open a support ticket. Something may be misconfigured in the bios or a chipset driver overwritten by MS update.

You might consider guest booting a stand alone linux system on the AMD mb and run similar tests to see if there is a consistent issue.

 

[Klueless]

I think you've done an awesome job of trying to narrow things down.

I guess I'm somewhat complacent. We've about ten Windows desktops and laptops scattered around at work. Even though they're all Gigabit Ethernet they all run at different speeds. My LAN based (PC to PC) speed tests all run faster than my Internet Speed tests. My LAN based speed tests typically run 6 & 700 Mbps. My Internet is only 400 x 20 Mbps yet only one of my PCs can achieve that speed. 150 to 250 Mbps is more typical.

Most of our PCs are either cheap and/or old. The one PC that can keep up with my Internet speed of 400 Mbps is definitely high end.

For me I don't really care. 100 Mbps plus is fast enough for us and I know no one is going to be hogging up bandwidth, e.g., 3 or 4 PCs running at full clip ain't going to saturate my down link : -)

 

[rmiller1959]

Oh, my wife seems content with her Internet speed - the geek in me is challenged by this mystery, however!

 

[rmiller1959]

Well, the one thing that stands out to me is the AMD chipset versus all the other Intel chipsets.
You could try an Intel nic in that mb, but i would do some research on the mb manufacturer’s support site first, maybe open a support ticket. Something may be misconfigured in the bios or a chipset driver overwritten by MS update.

You might consider guest booting a stand alone linux system on the AMD mb and run similar tests to see if there is a consistent issue.

Those are good suggestions - the NIC is essentially the same as the one in my machine, and I've updated to the latest Realtek drivers, so it has to be something related to the motherboard. Thanks for the checklist!

 

[rmiller1959]

BTW, I connected another cable (Cat 6) to the same port on the router, and then to the desktop and the laptop, and ran Speedtest. I obtained the same results as with the other cable - 108.56 download/8.37 upload on the desktop, 317.66 download/9.98 upload on the laptop.

 

[ColinTaylor]

I would go with @degrub's suggestion and boot from a Linux live CD/DVD. That would tell you if it's a software issue on the PC.

 

[rmiller1959]

I thought I would close the loop with everyone on this topic. After numerous types of tests, I've narrowed it down to either 1) a problem with the AMD chipset on the motherboard or 2) a software problem. I even installed a standalone Intel gigabit Ethernet adapter using the PCI-E x 1 slot, with the same speed result. On a related note, I added another desktop computer to my network with an Intel chipset and it reaches the Internet speed levels for which I'm paying, Based on all of that, I've decided to purchase a new motherboard with an Intel chipset and processor, and see if that changes things. I'll keep you posted!

 

[rmiller1959]

In case anyone is still interested, I installed a new motherboard with an Intel chipset and a Pentium Gold G5400 processor into my wife's machine today to test the theory that the AMD chipset was the limiting factor in my wired Ethernet connection's internet speed results. I did not do a clean install of Windows; I wanted to keep things as they were to determine if the new hardware would make a difference. It did - I hit 340 mbps at one point during my Speedtest trials. I don't know why the AMD chipset would inhibit the internet speed, but it appears to have been the culprit.