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I recently started renting out a room to someone who has a Windows-laptop.

Everything we have is Apple (2 Macbooks, 1 iPad, 2 iPhones, 1 iMac) connecting to an Apple Airport Extreme which extends the internet from the modem/router we got from the ISP. The network is perfectly stable and I have no problems using it in the other apartments in this building. (3 apartments in total).

But since the new renter moved in, the Internet gets really unstable as soon as his computer connects to it. It's not the WiFi-signal, because that works fine (I can stream from one device to the other without a problem when the internet is "down"), but when he connects his computer, the Internet just stops working about every 10 minutes. It takes a minute before the internet is back up again.

One weird thing: Torrents keep on downloading and uploading, even though the Internet is "down" (I can't browse to any page while it's "down").

I tried Google, but the results all point me to Windows laptops crashing when they connect to the WiFi, not the Internet itself. I checked and it's on every device using my Internet connection. Also my Wii U and my GF's Kindle (I have nothing connected through an Ethernet-cable, so I can't say if that works). Also, whenever classmates come over to do homework, they can connect without a problem and without killing the Internet connection.

I hope someone can help me out, because I can really not live with an unstable Internet-connection for 6 months, haha! Now using my iPhone for tethering, but I would much rather just use the WiFi.

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closed as too localized by Ƭᴇcʜιᴇ007, Diogo, BBlake, 8088, Canadian Luke Dec 13 '12 at 0:58

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

    
Can you get the laptop in-hand for testing? If not, there's probably nothing you can do to figure it out, just deny their access if it keeps happening. –  Ƭᴇcʜιᴇ007 Dec 12 '12 at 12:27
    
I can probably get it for testing yes, but what tests should I do? –  Rvervuurt Dec 12 '12 at 13:24
    
If torrents keep working then 'the Internet' is not down. :) What elese keeps working? Anything which already has a connection? Anything which does not need a DNS lookup? (e.g. go to a webpage, plug in the windows laptop, try to reload that webpage from the first computer. Does that work but do other (new) pages fail?). Etc etc. –  Hennes Dec 12 '12 at 20:57
    
That Windows laptop could be infected with viruses that sends rougue DHCP messages to redirect traffic to it. This comes in multiple forms, but in your case it seems it interfered with the DNS server settings. You may want to take a note of the value before and after. –  billc.cn Dec 12 '12 at 20:59