Odd Networking Issue

By Joseph Zollo
in Smart Home, Network & Security

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Grand Master

Joseph Zollo

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Posted

So normally i'd be able to troubleshoot this on my own but this just doesn't make sense (to me at least).

My network is configured as follows...

Cable Modem -> Linksys WRT54G -> Linksys EG008W Gigabit Switch -> (PC1 & PC2)

PC1 is my desktop and everything is working just fine.

PC2 is my laptop and that's where the problem lies, whenever connected to the switch I get insanely slow internet/network speeds (see my speedtest below). HOWEVER, when I connect directly to the router, everything is fine. I am trying to understand why everything is fine when I connect directly to the router, but when I connect to the switch, everything gets slow. My upload speeds are normal, the only issue here is the download.

Both computers run Windows 7 Ultimate. I have other devices on the network, but for troubleshooting purposes I disconnected them and the problem still persists.

Here's a link to my Speedtest on PC2...

1119807884.png

Things i've tried...

- Reinstalling the network card drivers for PC2

- Full format/reinstall for PC2, Windows 7 Ultimate x64

- Replaced CAT5e cables

- Different ports on the switch

- Different protocols (FTP d/l speed is the same as HTTP)

I'm honestly at a loss here, if anyone could offer some insight or suggestions, i'd appreciate it greatly!

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https://www.neowin.net/forum/topic/969784-odd-networking-issue/
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Grand Master

+BudMan MVC

Posted
  • MVC
Posted

And is your laptop connecting at gig or 100 or 10? Do you have any issues with the duplex, if there is a mismatch in the duplex your connecting is going to be insanely bad!!

Btw I would take your router out of the picture for speed tests -- test the speed between your PC1 and PC2 using robocopy and a large file or iperf is good testing tool for bandwidth.

http://sourceforge.net/projects/iperf/

Grab the java version, it has the exe in the download you can use directly.

Grand Master

Joseph Zollo

Posted
  • Author
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So after some more tinkering, I believe I have found the issue.

I manually set the laptop (PC2) to 100Mbps Full Duplex, and my speed issues were resolved, but manually setting to 1Gbps Full Duplex, everything gets slow again (only download, upload is fine as always).

In a few minutes I am going to be reverting the driver to a previous version and see if anything changes.

Edit: Old driver installed, no changes.

Grand Master

+BudMan MVC

Posted
  • MVC
Posted

Well your router clearly does not have 1gig interfaces.. But that really should not cause a problem having gig to switch, and then 100 to your router.. Is your desktop running gig?? If not, or you don't transfer any data between your pc2 and pc1 there is no point to running gig anyway.. So if setting your pc2 to 100mbit fixes the problem - there you go ;)

edit: you know one thing you could try, just a guess really but have seen some weird issues with it is turning off autotuning.

netsh interface tcp set global autotuning=disabled

You can always just set it back to normal again if doesn't fix the problem, but I normally turn it off because I have seen it cause some weird stuff with speed of file transfers.

you can view your current settings with

netsh int tcp show global

BTW your going to want to run these from an elevated prompt.

edit2: here are my current settings.

C:\Windows\system32>netsh int tcp show global

Querying active state...

TCP Global Parameters

----------------------------------------------

Receive-Side Scaling State : enabled

Chimney Offload State : enabled

NetDMA State : enabled

Direct Cache Acess (DCA) : enabled

Receive Window Auto-Tuning Level : disabled

Add-On Congestion Control Provider : ctcp

ECN Capability : enabled

RFC 1323 Timestamps : enabled

Grand Master

Joseph Zollo

Posted
  • Author
Posted

PC1 is connected to the Gigabit Switch @ 1Gbps.

I also added PC3 into the mix, which is a file server running Windows XP, it's connected to the Gigabit Switch @ 1Gbps as well.

PC1 can pull files off PC3 at ~40-50 MB/s, which is average for a gigabit connection, PC2 can pull files at ~10-12 MB/s when in 100Mbps/Full Duplex mode, but when I set the speed to 1Gbps/Full Duplex mode (or Auto-Negotiate) I get <1Mbps transfer speeds.

So basically, the network card on PC2 (Laptop) works fine in 100Mbps/Full Duplex mode, but won't function properly when switched to 1Gbps/Full Duplex or Auto-Negotiate. It's not a big deal if I don't get Gigabit speeds, but I would like to pinpoint the problem and work on a fix.

Grand Master

+BudMan MVC

Posted
  • MVC
Posted

Well you could boot the laptop with a liveCD and see if you get the same problem - if works fine this would point to a driver issue. if still has same problem then points to problem outside of the OS/Driver. Be a problem with the actual card or just something with that switch and nic that doesn't play nice?? Weird issue to be sure.

Do you have another switch you can try?

Really curious what happens when you boot a liveCD? There are quite a few linux liveCDs to choose from that are small in size - damn small linux only like 50MB, or mint has a 700MB version, etc.

Grand Master

+BudMan MVC

Posted
  • MVC
Posted

yeah thats kind of a large liveCD, I would of gone with something a bit smaller ;)

30M http://distro.ibiblio.org/pub/linux/distributions/slitaz/iso/stable/

50M http://ftp.heanet.ie/mirrors/damnsmalllinux.org/current/dsl-4.4.10.iso

<600M http://lubuntu.net/

700MB http://www.linuxmint.com/edition.php?id=67

etc.. ;) But sure that will work - just take a bit longer to download.

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