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.
