Wireless works okay but no LAN

[tontoe]

Hello all
I have a 7800N which has worked like a dream since I bought it about a year ago.

Then today, my wired network just stopped working. I have an Ethernet cable connected to a 6 port switch in my office, and another to a 4 port Netgear gigabit switch in my living room.

I suspected switches or cables initially, but I have tried to connect directly to the router via an Ethernet cable with two different laptops, and I get the much-loved "unidentified network" or "limited or no connectivity" message relating to the local area connection.

I have restarted the router three or four times and done to resets - problem remains.

IPCONFIG reveals my desktop has an auto-configured IPv4 address of 169.254.0.183 (which looks right?) but no default gateway.

Can anyone help?

[tontoe]

forgot to mention that I can access the router's configuration page via wireless...

[Tomken]

The 169.254.x.x isn't a valid IP address which will allow you to connect to the Internet - it should be similar to the IPv4 preferred address of the working wireless adapter.

Read through this article to see if it will resolve this condition http://www.corenetworkz.com/2008/02/how ... ng-is.html

While the latter netsh cmds need to be run from the cmd prompt as an Administrator if using Vista or later Windows OS, run all of the cmds as an Admin so that you can follow the ipconfig /flushdns with ipconfig /registerdns before going onto the netsh cmds.

Which AV are you using ?

[tontoe]

Hi

Thanks for this.

Very useful article - explained the IP address clearly.

I tried all the steps and could still get no connection, but I learned some useful diagnostics.

I tested the Ethernet cable from the office to the router with a LAN tester and that came out okay, but I swapped the cable anyway. Still no joy.

On a hunch, I swapped the 8-port switch for the 5-port switch and... bingo! I had a valid IP address again.

Strange thing is, I decided to power up the 8-port switch and try it again, and it worked too.

So the problem seemed to be the switch, cured by powering it down (i.e. pulling out the power supply jack).

I know practically nothing about networking, but I know a little more now! Thanks for your help.

[Tomken]

Glad to hear that you've got it sorted and while I know nothing about switches, it sounds as though you've done the equivalent of a Power Cycle which can often restore connectivity.

A power cycle is where you switch off the modem (if applicable), router and computer and disconnect all cables.

After leaving the modem and/or router off for a min of 30secs, switch the modem back on, allow it to initialize then do the same with the router as you wire it back up and then finally switch the computer back on where you should end up with a valid IP address.

If you still cannot connect after that, then disabling the AV can sometimes resolve and temporarily disabling the WPA security in the router can do it - re-enable afterwards whether it resolves or not.

Checking that you aren't using a Proxy server (if you don't normally use one) will also restore connectivity and this is done (if unable to boot IE) via typing temp from Start then clicking on Change temporary Internet settings/Connections/LAN settings and ensuring that the only box ticked is that for Automatically detect settings.

If the Proxy server box has been checked, then that could have been from default or by an infection and an infection can also deny connectivity, so a quick scan with something like the free version of SuperAntiSpyware http://www.superantispyware.com/ should probably clear out any infection.

The other cmds in the previous article, especially the winsock cmd can also resolve connectivity.

[tontoe]

Thanks - yes, think I'd done the power cycle, only turned everything off but the switches and not disconnected the Ethernet cables from them. I'll know next time!