DELL randomly drops Internet connection yet still talks to router

Ed_Jogg

This is driving us mad. Our DELL desktop, running Vista (yes, I know) works happily with its Internet connection, most of the time, but then loses it, with no apparent provocation. Recovering connection is difficult. Any ideas as to what is happening? What do I need to look for? How do I recover without needing Admin access? How do I stop it happening?


OK, that's the summary! Here's some more detail...
The PC is connected by an Ethernet cable to a wireless router, itself connected by Ethernet to the cable modem. When connection from the PC is lost, the laptop can still connect happily via Ethernet or wireless (USB dongle). Rebooting the PC doesn't, in itself, restore connection.

At first, I discovered that the diagnostic link provided by the Internet Explorer 'can't find server' page did the trick. Diagnosing the problem, it suggested resetting the Network Adapter (which requires Admin access), but this did indeed get it working again (rather slowly, as the diagnostics take several minutes to run). It would be useful to know how to reset it without having to run through the IE diagnostics first.

More recently I found this trick wouldn't work: Windows 'could not diagnose the problem', and didn't provide the 'reset' link. Somewhat surprisingly I managed to call up the router control pages in the browser window and was able to select 'reboot' (this obviously requires admin access to the router). This worked. But these recovery solutions are no good for my wife, who is not particularly computer literate.

I need to stop it from happening in the first place. How can the PC connect to the router (and display/navigate round its in-built webpages) but not be able to connect through the router to the Internet?

Where do I start looking, and what for? Help! please?
(Also, if there's a better site to ask the question, please advise...)

penrhyn

When you lose connection, what is the state of the internet light on your router.
Could you additionally log on to your router and post your line statistics.

Ed_Jogg

The internet light, from what I can remember, is fine -- certainly stays green -- might be flickering. I've seen it go amber when the connection is lost (did this when I rebooted it).

Don't know where to find the line statistics. The router is a D-Link DIR-615. I called up the router page and looked around all the tabs but cannot find 'line statistics'. I vaguely remember seeing some such when examining the previous ADSL router (which had a vaguely similar, though less frequent problem), but now we're on cable and the (new) modem and (new) router are separate boxes.

Fairwinds

Same thing is happening to me over last 3 days - Dell Laptop and virgin media also vista.

Light on modem normally stops flashing and light stays on

Also says local access only and quite often tries to aquire Ip address

penrhyn

Have a look here, some D-Link routers listed.

http://www.kitz.co.uk/adsl/frogstats.php

Ed_Jogg

While waiting for the first reply to my original post, I Googled "reset the network adaptor", the instruction provided by IE. The number of hits suggested this was clearly a widespread problem related to Vista PCs, although there were no clear answers. Fortunately, on a forum thread I found a link to a Microsoft help page that sounded hopeful:

"Windows Vista cannot obtain an IP address from certain routers or from certain non-Microsoft DHCP servers"

The page explains the scenario and the cause, but the key cause is:

"In Windows Vista, the BROADCAST flag in DHCP discovery packets is not disabled. Therefore, some routers and some non-Microsoft DHCP servers cannot process the DHCP discovery packets.

In this scenario, Windows Vista cannot obtain an IP address."

The page provides a 'Fixit' that can be downloaded, which, when run, modifies a registry bit to (presumably) disable the Broadcast flag. (Don't worry, I don't really understand what I'm writing either!)

I ran the fix four or five hours ago, and the problem has not yet re-occurred. Unfortunately, that is not conclusive, as the failures were only occurring hours apart (when I was using the computer) -- unless my wife was using it, when it failed immediately! However, it does make sense to me. The fault -- which we had seen previously, but much more rarely, on the same computer connecting wirelessly to an ADSL modem/router -- does give the impression that the computer is connecting to the router, but is not connecting through this physical connection to the internet. If the PC loses its (ability to obtain an) IP address, I would expect it to behave in exactly this way.

Fingers crossed...

Ed_Jogg

Still seems to be OK...

Fairwinds

Does that explain why it has only started being an issue of late - last 3 or 4 days for me.

I was thinking it was to do with some windows updates?

Ed_Jogg

A Windows update might explain your timing, but it won't explain ours --
(a) because it was triggered by a change of physical connection (USB --> Ethernet), and
(b) because something has corrupted a write-protect bit somewhere, and Windows can no longer check/download updates :mad:

(Windows Updates since fixed -- see later post.)

Ed_Jogg

:mad: :mad: Grrrrrr -- Spoke too soon! :mad: :mad:

Was out for evening, straight from work; came back late to find 'nothing working' and OH very annoyed.

Well, router appeared to be happy -- power, internet, wireless, 2 x Ethernet lights, all green and occasionally flickering -- but neither of the PCs was. Both PCs had lost internet connection.

Recovery process:
(1) - (Vista PC) - start Internet Explorer - wait for page load to fail - express surprise because router address is now one of the home page tabs, and PC cannot even connect to this! Oh dear.
(2) - (Vista PC) - start IE diagnosis process - wait for solution "Reset network adapter" to be offered - select this - wait for process to complete
(3) - (Vista PC) - Refresh tab linked to router - see router page appear - good - try another page - no good - bother
(4) - (XP Laptop) - start IE diagnosis process - note that it behaves differently from other computer (different OS, different IE) - express annoyance when it says it cannot fix the problem - express surprise when offered a test log for the process - save test log to hard disk - note reported error
(5) - (Vista PC) - log-in to router and select 'Reboot' - watch lights wink out on router and reappear - when complete, try refreshing a web page - all comes back to life
(6) - (XP Laptop) - try refreshing a page - all OK - no further action required

So, (a) the previous fix did NOT cure the problem, (b) whatever went wrong with the Internet connection on the Vista PC was enough to knock out the router too, and (c) the laptop connectivity issue was almost certainly limited to not being able to connect to a now non-working router, re-confirming that problem is with the Vista PC. This is not good.

Any ideas please?

If_it_can_go_wrong

Do you leave the router and modem powered up when not in use? I ask because under some setups the router can lose it's connection with the internet through the modem and fail to reestablish itself.
I found the easiest way of avoiding this was to switch the router and modem off at the wall when not in use. This way when you switch back on it forces everything to reboot anyway and is usually fine for hours at a time.