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I have this network issue with windows7 on a laptop, the connection suddenly drops, sometime at laptop->modem, sometime at modem->isp, sometime both. The ADSL modem is on autodial and become DHCP server, should be plug and use for pc.

I believe this is not modem/router problem, but with windows7 itself. Reason is the modem settings is never touched, the win7 is new pc however.

My previous winxp pc have no such problem, connection lasts almost forever/weeks without unknown connection drop.

I also notice, win7 sometime did not detect the net cable plugged in, even if i tried it multiple times/disable/diagnose. Resetting the router/modem or reboot win7 and it will. Manual IP also doesnt solve the problem. Laptop has been open once for display replacement, could this have effect on net card ? If so, how come i still able to browse ?

Is there someway to solve this ?

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I suppose I should start by asking if possibly you just have a loose ethernet connection? That is, could your laptop actually be physically disconnected from your router when either the cable and/or the connector is "jostled"?

Assuming there are no problems with the physical connector, then it would help if you provided some other detail. Could you open a command prompt on your Win 7 system ... I don't recall if it needs to be elevated or not ... and do ipconfig /all both when your connection is working and then again after it has dropped? This will display some basic info about the IP addresses established by DHCP with your router.

If the results of the ipconfig are different after the connection drops then please cut'n paste the info and add it to your answer so we can see what's changing.

When your connection drops, are you still able to ping the IP address of your router (the default route shown in ipconfig /all)?

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I understand what youre trying to ask. Its a bit complicated here since the router->isp too sometime affected, which I found a bit weird. The answer to your question : The connection is totally drop, its like you pull out the cable. Add: I just check the modem log, and found this.. 7/16/2010 8:28:21> LLC 1483 unknow protocol IMHO If firmware/driver is outdated, it still wont affect connection. On network protocol level, everything is disabled/removed except IPv4 only. Is there a new IPv4 protocol stack ? LOL Aww there it goes again. The LAN is ok but ADSL dropped. sucks. – afifio Jul 22 '10 at 4:04

I think i found whats is the problem.

Windows7 UPNP is broken. I trace similar problem and found the response on microsoft website.

The suspect is UPNP, disable it on the pc AND the router. I'm still testing it, its been few hours already, and still no connection drop...yet.

It is certainly microsoft fault, the networking module have lots of problems and still inside since windows7 beta.

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I am happy to hear you may have solved your problem. However, claiming that "It is certainly microsoft's fault" seems a bit of a leap at this point when you still don't IMO completely understand why it failed previously. Assuming you are right and your problem is related to UPNP, how do you know the problem is not in your router's firmware? BTW, what make/model of router are you using anyway?? – irrational John Jul 22 '10 at 13:18

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