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I'm using a SMC2804WBRP-G router connected to my ADSL-modem. Usually there are two computers connected to this router: a win7 ultimate desktop(wired) and a macbook air (wireless). Both working absolutely fine and never caused any connection drops as far as I know.

A new room mate moved in last month and each time she starts up her win7 home laptop the router looses the internet connection. The laptop is on a wired connection.

The first time she connected to my router, the connection dropped every 2 mins. To find out whats wrong with her machine I disabled all unnecessary services etc. besides the anti virus software. That helped to eliminate almost all of those periodic connection drops. But the start up drop remained and I've got the feeling that the router is still loosing connection from time to time.

I haven't had the time to find out what service caused the periodic drops. But I'm more concerned about is that start up drop.

Can anyone point me in the right direction to look for the problem? I would be very thankful for any hints or tips!

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Sounds like the computer has a fixed IP address. Change it to DHCP and see if that helps. – user3463 Jan 6 '11 at 20:04
I'll double check that. But I'm pretty sure its not fixed. – Per Jan 6 '11 at 20:09

The new laptop may be infected with a botnet virus. The traffic may be detected by the ISP and the modem disabled. When the connection goes down, is the ADSL modem still connecting to the Internet?

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I think it's a good idea to scan all the machines on the network now, simply because a virus is a possibility. If this does happen, make sure they're not plugged in to each other, to prevent any possible spread of infection. – user3463 Jan 6 '11 at 20:14
I think not. Its reconnecting pretty fast. But for the time the drop happens I'm not able to access my router's controls. I've been monitoring my connection via wireshark when those periodic drops occurred and I think I've seen some sort of RST (reset) command being send by either the router or the laptop. But I didn't bother to look into that because disabling her services helped a lot and hadn't had the time back then. – Per Jan 6 '11 at 20:15
RST is just a standard part of the IP stack. What do the status lights on the modem and the router do when there's an outage? – Ex Umbris Jan 6 '11 at 20:18
Mmh, I'm gonna have to check that tomorrow morning. She's already asleep right now ;-) – Per Jan 6 '11 at 20:28
So I've just experienced another drop and the router completely lost connection. I had to reset the router by pulling the plug, because I couldn't even get a connection to it directly. – Per Jan 8 '11 at 14:39

It's a simple fix. If you listen to these tech guys they'll have you running around in circles:

  1. Click on start,
  2. Click on control panel,
  3. Double click on network connections,
  4. Right click on the internet connection you are using,
  5. Click on properties,
  6. In window click on Internet Protocol (TCP/IP) to highlight it,
  7. Click on properties,
  8. At bottom click on use following DNS server,
  9. At Preferred DNS server enter,
  10. At Alternate DNS server enter,
  11. click OK, close everything out.

If you follow these directions it should solve your problems.

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