On R7000P ethernet suddenly slowing down

Post new topic   Reply to topic    DD-WRT Forum Index -> Broadcom SoC based Hardware
Author Message
shuang
DD-WRT Novice


Joined: 24 Oct 2023
Posts: 5

PostPosted: Tue Oct 24, 2023 20:12    Post subject: On R7000P ethernet suddenly slowing down Reply with quote
I have R7000P running DD-WRT v3.0-r53544 and two PCs running Windows 11 connected to it using Realtek 2.5G Ethernet adapters.
Suddenly on the one of the PCs speed drops from Gb/s to Kb/s when copying files in Windows. It is still possible to copy files from another PC to that PC with the full Gb/s speed, so the speed loss is asymmetric.
Restarting Ethernet with the Restart-NetAdapter -Name "Ethernet" PowerShell command helps to restore speed.
What this could be and how I can perform some diagnostics?
Sponsor
tedm
DD-WRT Guru


Joined: 13 Mar 2009
Posts: 554

PostPosted: Wed Oct 25, 2023 6:55    Post subject: Reply with quote
at windows command line

netstat -e -s

run this multiple times during the problem

see if the TCP Statistics for IPv4 "Reset Connections" "Segments retransmitted" suddenly start
jumping

Or you can use a GUI method this way:

https://www.clouddirect.net/knowledge-base/KB0011163/checking-for-tcpip-packet-loss

And most importantly buy yourself a high quality 8 port managed switch. If you are still getting slowness from pc to pc when using the ethernet switch then your problem has nothing to do with dd-wrt.
shuang
DD-WRT Novice


Joined: 24 Oct 2023
Posts: 5

PostPosted: Wed Oct 25, 2023 7:48    Post subject: Reply with quote
tedm wrote:
then your problem has nothing to do with dd-wrt.


Yeah, it seems so. The retransmission rate is about 10%. Tried iperf, it gives normal values. Must be something with SMB.
tedm
DD-WRT Guru


Joined: 13 Mar 2009
Posts: 554

PostPosted: Fri Oct 27, 2023 14:38    Post subject: Reply with quote
I would guess the Realtek network drivers in Windows are the problem. If you were to swap the ssds in your 2 windows machines and load Linux on both of them very likely copying over SMB between Linux boxes would work fine. If you look at the Linux source code for Realtek drivers there are all kinds of programmers comments about various hardware bugs in the chips.

The Intel network chips are used in most of the performance tests that are published online for this reason. Intel worked closely with the OSS community when they developed their networking chips and learned a lot about how to properly design adapter silicon.

Realtek has released multiple Windows drivers for their chips. It's harder nowadays with windows 11 to try them out but still possible.
shuang
DD-WRT Novice


Joined: 24 Oct 2023
Posts: 5

PostPosted: Fri Nov 10, 2023 18:46    Post subject: Reply with quote
What I have found so far is that speed drops to 4-6 MBps s instead of KBps when "Large send offload" both for IPv4 and IPv6 is disabled in driver settings. Disabling all power saving settings does not help.
tedm
DD-WRT Guru


Joined: 13 Mar 2009
Posts: 554

PostPosted: Fri Nov 10, 2023 20:46    Post subject: Reply with quote
Are you disabling it on the windows PCs or the router? This is discussed here:

https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/ntddndis/ns-ntddndis-_ndis_offload

And also here:

https://atomicit.ca/kb/articles/slow-network-speed-windows-10/

Not favorably. Also Mbps is faster than KBps do you have a typo in your post by any chance?
PaulGo
DD-WRT User


Joined: 01 Dec 2021
Posts: 289
Location: Maryland, United States

PostPosted: Sat Nov 11, 2023 17:35    Post subject: Reply with quote
I also have the R7000P router. Realtek has two types of drivers. One of them is without power savings. See if that helps. I have not transferred files between computers, but I got reduced performance with the power saving driver.
shuang
DD-WRT Novice


Joined: 24 Oct 2023
Posts: 5

PostPosted: Mon Nov 27, 2023 17:50    Post subject: Reply with quote
tedm wrote:
Also Mbps is faster than KBps do you have a typo in your post by any chance?


Strangely, these mysterious speed drops end in better performance when Large Send Offload is disabled on NIC. But they still happen. I didn't change DD-WRT offload settings.

I tried energy saving drivers, but found no difference. As I understand, with these drivers energy saving is simply disabled by default in the advanced NIC settings. Performance still drops mysteriously.
shuang
DD-WRT Novice


Joined: 24 Oct 2023
Posts: 5

PostPosted: Wed Nov 29, 2023 20:04    Post subject: Reply with quote
Today I rebooted the router and found the same slowdown from the moment of boot on all my machines.
I suppose either I have faulty hardware, or there is a systematic problem in dd-wrt, that was missed because of some unusual conditions. The slowdowns happen with a considerable uptime, and all my machines have generally large one (either constantly on or use hibernation). Also the internet speed is OK, only the intranet ethernet speed becomes low. I also had sometimes the same problem on my previous Netgear WNDR4300, but much more rarer.


Edit:

It turns out that this is an issue with cables. Somehow shielding the cable with aluminum foil in the places where it contact other cables helps to get a stable connection. Will replace my UTP cat 5e with 6.
Display posts from previous:    Page 1 of 1
Post new topic   Reply to topic    DD-WRT Forum Index -> Broadcom SoC based Hardware All times are GMT

Navigation

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum