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Extremely slow LAN connection



I have 2 computers connected through a Linksys SE2500 ( http://www.linksys.com/en-apac/products/switches/SE2500/). It's either CAT 5e or 6. There is 20 feet of cable total, maybe.
The 2500 is connected to another router.
The PCs are Windows 7 home and Windows 7 pro. Working off the home PC to the pro PC is amazingly slow. We're talking 50kb/s. Yes...KILO. Trying to navigate folders is painfully slow. If I go to the pro and copy to the home machine it's fast.
Internet connection is fine on both PCs.

It did not used to be like this...obviously I changed something but I'm not sure what it was.

Both PCs have MS Sec essentials. Connection to the 'net is fine.

I started a new thread because the fixes on other threads didn't work for me.

The home PC only has 100Mb speed via it's laptop port. The pro machines a realtek GBe motherboard port.

I turned off RDC, speed and duplex on auto.
I pinged the pro from the home and no packet loss.

Does anyone have any ideas?

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How are you doing a copy, are you running homegroups?


Lets actual speed test we can use..  Robocopy is part of windows u can use that to copy files between machines so we can see tests.  Also lets do a network test for speed with say iperf or netio




Simple exe - you copy the exe to both machines.  On one machine you run with -s as the server, and then on other machine you run with -c ipaddressorname of the server machine and lets see some results


Or netio



So here is example of iperf in one direction where is the server..  Lets see your test in both directions





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check your event logs and processes in task manager...anything weird standing out that is or could be hogging bandwidth? When is the last time you scanned for viruses/ malware  and other critters?  MS Security Essentials has been known to let things thru and not take care of them...How long has it been since you updated the network drivers in the home machine? good luck!

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I'm cutting and pasting to copy.

There is no homegroup on this part of the network.  This switch is connected to the main router which has a wired PC that has a homegroup but neither of these PCs is part of it.

For the record, I am using a USB2 to giga adapter on the Home now.  It seems to work fine.


Home to Pro iperf

Microsoft Windows [Version 6.1.7601]
Copyright © 2009 Microsoft Corporation.  All rights reserved.

Client connecting to propad, TCP port 5001
TCP window size: 64.0 KByte (default)
[  3] local port 57726 connected with port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   300 MBytes   252 Mbits/sec


Pro to Home

[  4] local port 5001 connected with port 50064
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-10.0 sec   313 MBytes   261 Mbits/sec


I will say this... I did a bunch of troubleshooting w/different cables and plugging NIC to NIC and behavior is bizarre.  It's almost like the Pro with the integrated NIC LAGS.  Browsing from the home will be superfast like you are on the Home's C: and then it's incredibly slow.

LIkewise, grabbing a file on the Pro and dumping it on the Home gets 'calculating' then 25Kbs, then 2Mbs, then 2.5, 3, and eventually 4 or 5Mbs. 

The Home will drop a file on the Pro @ 23Mbs (according to Windows).  A 7Mb file is so fast that it doesn't even show the copy windows it just ends up where you want it.


Sorry to take so long to reply.  I guess I didn't subscribe to my own thread./f

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Lets be clear about something -- the driver was not the problem.  Drives don't all of a sudden just say lets not work today..  Now if it had always been crappy speeds, then ok maybe the driver was bad..  But working fine one day, and then next day not working updating the driver is not a fix or a normal thing to do.


"It did not used to be like this...obviously I changed something but I'm not sure what it was."


Who says you changed anything - could of been a simple duplex mismatch, normally that shows us as slow both ways but.  But without actual numbers to go off of we have really no idea what speeds you were seeing compared to what your wire is, etc.


Did you happen to reboot your switch/router - you have one machine at 100 and other at gig.  Maybe the switch was not working quite right - did your other machine now come up 100 vs gig? etc. etc..


While I agree not a bad idea to be on current drivers - updating drivers or bios or firmware on a router doesn't fix new issues, if it was working fine yesterday and all of sudden doesn't work, updating such a thing makes no sense.  They don't break out of the blue is my point.


Glad you got it sorted..  If you want a speed increase for moving stuff between your machines - update from 100 to gig on your one machine,.  Your router has gig switch ports on it - so no reason to have a box only running at 100..

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Lets be clear about something -- the driver was not the problem. 



Do you feel like continuing with this?  The connection is usable now but I would like to tweak it to best performance.  If so, ...


I did reboot the switch but I had rebooted it several times during the last day doing a bunch of troubleshooting. 

I do have gig on the Home PC.  It doesn't say that in the OP but I updated the info in the 2nd post.  I don't know if this is 'true'giga' because it passes through USB 2 but it is surely faster than my laptops 100mb RJ45 port.  The highest speed I've seen is 23Mb/s during a copy.



It is set as

Auto Negotiate

jumbo disabled

flow disabled


The Pro has a realtek GBE Gb

Auto negotiate

Jumbo off

When I updated the driver it reverted to default settings.  I had disabled green/engergy efficient settings and they are back on.


I just copied (ctrl-c) and dropped gigs of pictures to the Pro machine.  Windows says about 14 Mb/s.

Iperf log -

Home to Pro


274 Mbytes 230 Mbits/s


Pro to Home

Connection times out.  I have iperf listening on .1.146 as -s

I am using iperf -c .1.147 -w -256k.  It's ignoring the 256k and times out.

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23Mb/s during a copy.

Do you mean Mbits or MBytes here? B is Bytes, b is bits - huge difference ;)

"I am using iperf -c .1.147 -w -256k. It's ignoring the 256k and times out."

Not sure why your hiding the first part of what I have to assume is a rfc19118 address 192.168, 10., or 172.16-31 -- is that just a shorthand?

"230 Mbits/s" on your first paste while not really great for gig.. I normally see 800+ sometimes low 900's, you can try it with different window sizes that is the what the -w is, I like testing it with large window size because going to give you higher numbers and closer to the window size you should be using in normal file copies, etc.

230Mbps should roughly be 230/8 = 28MBytes per sec.. Why your not seeing higher numbers could be lots of things, could be just your switch being crappy.. Could be driver issue in this case. Could be odd ball settings on the driver or in the OS for tcp. Could be 3rd party firewall software?

I don't like that you can not connect the other direction - this would point to firewall setting, did you run iperf with elevated permissions, ie run you cmd prompt as admin before you run iperf.

We should really look into why that is not working so we can get the speed in both directions. Does your robocopy work in both directions - if so what speeds to do you see in that. What I would take from your iperf test is best you could see is about 28MBps no matter what since that is the speed on the wire so disk access unless slower than that would not be a bottleneck, etc.

While green settings can cause problems sometimes - once you have speed tests going in both directions you could try turning that on or off and seeing if you see differences that matter, etc.

So can pro ping the home IP? Can you access file shares off of it - if so iperf not working really points to firewall settings.

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