Nicolas314

All my geeky stuff ends up here. Mostly Unix-related

Windows 7 network disconnections

with one comment

Problem: I have a Dell laptop under Windows 7 connected to a GBit LAN. The network link keeps disconnecting as soon as I leave the machine unattended for more than 10-15 minutes. This breaks down all connected network shares, running downloads, connected IM sessions. It also happens during Webex conf calls, Skype sessions, or any other activity during which I am actively using the computer but not touching any input device.

Re-connecting to the network takes about 30-60 seconds, time enough for the other connecting party to leave the conf call wondering why I shut them down.

After about a month of trial-and-error it seems I finally found a working solution, documented below in hope it might be useful to somebody else.

Attempt #1: change energy settings

If you leave a Windows box unattended for long enough everything shuts down on its own, especially on laptops. Editing power saving settings seemed like a first thing to do.

    Control Panel
        Hardware and Sound
            Power Options
                Edit Plan Settings

Switching to “Never go to sleep” did not have the intended effect: the machine effectively stayed awake but network was still lost. The only way I found to maintain Webex sessions alive was to random-click around in the browser to call up web pages and cause network activity.

Attempt #2: blame the network

Asked network admins about potential issues: seemed I was the only one suffering from random disconnections. Back to Windows.

Attempt #3: change network adapter settings

A copious amount of googling unearthed the fact that no matter what you choose for Power Plan Settings, a network card can still be turned off by the OS when it decides to. The only way to change that is to modify power management settings directly on network interfaces:

Open Network and Sharing Center
    Local Area Connection
        Properties
            Configure (top-right)
                Power Management
                    [ ] Allow the computer to turn off this device to save power

Still no joy.

Attempt #4: update network card drivers

This is Windows after all: the first thing you do when you have issues is reboot the machine and if it was not fixed, update all your drivers.

Dell laptops have interesting stories to tell about drivers: there are the ones you find on Microsoft through Windows Update, and a whole other bunch available on Dell’s web site. That is: if you are patient enough to click through millions of pages designed as an incredible maze of incomprehensible references, dead links and serial numbers.

According to Windows all card drivers are up-to-date, which pushed me onto Dell’s web site for further software. Abandon all hope, ye who enters here.

Attempt #5: look for dedicated software from Dell

Couple of hours spent on the site entering serial numbers, downloading files named like A12017402941.exe in large quantities, installing them, rebooting the machine, to no avail. The laptop got a boatload of crapware installed but network still failed after a random interval between 10 and 15 minutes.

Attempt #6: mess up network settings

Turned off IPv6, switched the address to fixed vs DHCP, changed DNS servers, started/stopped Internet sharing, all of the above one by one and then together. These had no effect whatsoever.

Attempt #7: keep pinging

Will it change with constant network activity? I wrote a short Python script to ping a remote server every ten seconds and left it to run in background. Still no joy. It seemed the only way to keep things alive was to animate input devices, and I refused to resort to Fischer-Price technologies.

Attempt #8: fix autodisconnect in registry

More googling, more information about the mysteries of Windows network configuration. Found on Microsoft support site: fire up regedit and change the key in

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parameters

Key name is autodisconnect, set by default to 15 minutes. Changed it to 65535 (0000ffff) seconds. It can also be temporarily changed from command-line by issuing:

net config server /autodisconnect:-1

It kinda worked for a couple of hours, and then not. Back to square one.

Attempt #9: voodoo

Still found on Google: somebody reported getting less trouble by changing a network card parameter you would normally never touch. Why not?

Open Network and Sharing Center
    Local Area Connection
        Properties
            Configure
                Advanced
                    Property: Link Speed & Duplex

Change value from Auto Negotiation to something corresponding to your LAN capabilities, e.g. 1.0 Gbps Full Duplex for a Gbit local network.

The network stopped disconnecting at that point. I have absolutely no idea which parameter or combination thereof changed this behaviour, but I can also safely say I do not give a damn as long as it works.

Advertisements

Written by nicolas314

Tuesday 22 May 2012 at 11:35 pm

One Response

Subscribe to comments with RSS.

  1. The Ethernet switch will set the highest speed it can when it is turned on. As workstations are added it can renegotiate the speed if necessary so that it is lower. Workstations power on. Workstations power off. Conditions change, the speed is renegotiated and it’s up to each network adapter to adjust when the speed changes. A poorly-written network device driver won’t adapt to those changes. As you’ve noticed, manually setting your network card’s speed was the fix for you at least. Some people have noticed that they can replace their internal network adapter with a USB-based Ethernet adapter for the fix (bypassing the poorly-written driver).

    Michael

    Thursday 2 July 2015 at 8:47 pm


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: