Progressive LAN Slowdown, Fixed by Reboot (Long)

[rodshea]

Hi,
My LAN speed, tested with LAN Speed Test 3.5.0, reading and/or writing files from one desktop computer to another, progressively slows down from 700 -750 Mbps to as slow as 3Mbps over a period of hours to 1-2 days. If I reboot both computers, and sometimes the router, the speeds go back to the 700-750 range. This became obvious when I replaced my NETGEAR 2700 router with a NETGEAR R7000, and noticed slow internet speeds.

To sort this out, I have simplified the network, and can now reproduce the problem without the internet. The simplest way to reproduce it is to set LAN Speed Test to read and write 10 10 MB packets from the X79 to the Z97, or vice versa, for 6 hours or so, and continue using the computers at the same time. This typically slows things down to about 100-200 Mbps. Strangely, when things get really slow, around 35 Mbps, the mouse pointer on the monitor becomes slow to respond to mouse motion. This reverts to normal when the computer is rebooted. I can get the read and write speeds up to 300 to 700 Mbps by rebooting both computers, and the rest of the way by rebooting the router first, and then each desktop.

I have the R7000 router connected to 2 computers. One is ASUS X79 Deluxe MB using the onboard Intel 82579V Ethernet port with the Intel 12.10.29.0 driver. The other is an ASUS Z97-A, using the onboard Intel I218-V, with the Intel 12.11.96.1 drivers. As best as I can tell, these are the most current drivers. Both computers current versions of 64 bit Win7 Ultimate, and Norton 360. The Ethernet cables are 5e and 6, and are 3-5 feet long and directly connect the router to the jacks on the back of the desktops, there are no switches or hubs in the system. I have an Arris cable modem wired to the router, an Epson printer and an iphone connected wirelessly to the router. FWIW, when the LAN speeds are slow, so are my internet upload and download speeds. When the LAN speeds are good, so are the internet speeds.

I have spent hours on the phone with NETGEAR. They made sure I had updated to the most recent firmware, and that I had properly rebooted the router afterwards. They had me change the MTU’s from 1500, to 1450, to 1400, and one other setting, maybe 1468, all to no avail. They also had me change the CTS, also to no avail. Ultimately, they declared the router defective. I replaced it with another identical one, which did not change anything. At that point, they said it was not the router, and they could not advise me about the network adapters. I can also recreate the problem replacing one desktop with an ASUS UL30VT with an Atheros AR8131 PCI-E Gigabit Ethernet Controller using the 1.0.0.14 WinDDK driver.

So far, I have tried the following with the LAN adapters. They are set to their defaults, except as follows. I have changed the link speed from AutoNegotiation to 1.0Gbps/Full Duplex on each desktop, no difference. I disabled the various power saving modes for the network adapters in power management, on both desktops, no change. I have disabled anything to do with IPv6 in the Adapter properties and the Windows Local Area Connection Status>Properties. I have simultaneously disabled all the IPv4 offloads. In all cases except the IPv4 offloads, I re-enabled everything before I disabled the next thing. In each case, I have made the change, run LAN Speed Test for x hours, and none of these changes seem to help.

I’m guessing that the problem is caused by one or more of the Network Adapter settings not playing well with the router. One thing to check might be individually disabling the offloads, but, other than that, I’m running out of ideas. What should I try?

Thanks,

Rod

 

[bill001g]

Does you iphone run slow on the internet when the pcs are acting up.

It would be extremely strange for the router to have any impact on lan traffic. Many routers have a separate chip to run the lan ports. It is many times exactly the same chip that is used in a 5 port switch. This is such a simplistic function since it is passing traffic based on mac address and it has no place to store data so it almost has to be the end machines.

I would first start with the resource monitor and see if anything stands out. If the packets are being transmitted but getting errors you would still see high network traffic levels even if it was getting errors.

I would also try a really simple tool called IPERF. This is a very old line mode command that runs totally from memory and is not CPU or memory intensive. It pretty much tests the network subsystem and since it is not reading or writing disk it is not influenced by much other than the network.

 

[rodshea]

Does you iphone run slow on the internet when the pcs are acting up.

It would be extremely strange for the router to have any impact on lan traffic. Many routers have a separate chip to run the lan ports. It is many times exactly the same chip that is used in a 5 port switch. This is such a simplistic function since it is passing traffic based on mac address and it has no place to store data so it almost has to be the end machines.

I would first start with the resource monitor and see if anything stands out. If the packets are being transmitted but getting errors you would still see high network traffic levels even if it was getting errors.

I would also try a really simple tool called IPERF. This is a very old line mode command that runs totally from memory and is not CPU or memory intensive. It pretty much tests the network subsystem and since it is not reading or writing disk it is not influenced by much other than the network.

 

[rodshea]

I will try the IPERF. The iphone speed stays stable at about 70Mbps per OOKLA or Xfinity internet speed tests. I do agree that this is something in the desktops' configuration hat is brought out by the faster LAN speeds that the router allows.

Thanks,

Rod

 

[rodshea]

I could not really figure out how to use IPERF or XPERF, but ResMon seemed to show a lot of DPC and interrupts when performance was slow. LatencyMon pointed to ndis.sys as the issue. I reverted to the most recent Network Adapter drivers on the Motherboards' websites, which helped somewhat. I then added TP Link RealTek based PCIE gigabit adapter cards, and used them instead of the Intel adapters. Sad to say, that seems to work. I would have liked to have found there was just one setting in the Intel driver that needed to be changed, but no such luck.

Rod