Windows periodically disconnects, reconnects to the network

connectionhome-networkingnetworkingwindows 7windows xp

Update 2012-03-27: It might be the physical connection from my cable modem to my provider. The cable provider says he's seeing disconnects of the modem, and they're sending a technician. (Also, please consider upvoting to help a low-rep user like me pay for his bounty…)

My setup:
I have a PC with a Gigabyte GA-MA78S2H motherboard (Realtek Gigabit wired Ethernet on-board). I have the latest drivers (at least the latest driver for the NIC.

I'm connecting via an Edimax BR-6216Mg (again, wired connection), to a cable internet provider (infrastructure provider is HOT, ISP is Bezeq Intl.).

For some reason I experience short periodic disconnects and reconnects. Specifically, Skype disconnects, tries to connect, succeeds after a short while; incoming SFTP sessions get dropped; using a browser, I sometime get stuck in the DNS lookup or connection to the website and a page won't load. A couple of seconds later, a reload works.

All this happens with Windows XP SP3. With Windows 7, it also happens. (When I initially wrote this question I didn't notice it.)

ipconfig for my adapter:

Ethernet adapter Local Area Connection:

    Connection-specific DNS Suffix  . :
    Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller
    Physical Address. . . . . . . . . : 00-1D-7D-E9-72-9E
    Dhcp Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes
    IP Address. . . . . . . . . . . . : 192.168.0.2
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Default Gateway . . . . . . . . . : 192.168.0.254
    DHCP Server . . . . . . . . . . . : 192.168.0.254
    DNS Servers . . . . . . . . . . . : 192.117.235.235
                                        62.219.186.7
    Lease Obtained. . . . . . . . . . : Saturday, March 10, 2012 8:28:20 AM
    Lease Expires . . . . . . . . . . : Friday, January 26, 1906 2:00:04 AM

A result of some tests a couple of the disconnects:

C:\Documents and Settings\eyalroz.BAKNUNIN>nslookup google.com

DNS request timed out.
    timeout was 2 seconds.
*** Can't find server name for address 192.117.235.235: Timed out
DNS request timed out.
    timeout was 2 seconds.
*** Can't find server name for address 62.219.186.7: Timed out
*** Default servers are not available
Server:  UnKnown
Address:  192.117.235.235

DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to UnKnown timed-out

C:\Documents and Settings\eyalroz.BAKNUNIN>ping 194.90.1.5

Pinging 194.90.1.5 with 32 bytes of data:

Control-C
^C
C:\Documents and Settings\eyalroz.BAKNUNIN>tracert -d  194.90.1.5

Tracing route to 194.90.1.5 over a maximum of 30 hops

  1    <1 ms    <1 ms    <1 ms  192.168.0.254
  2     *        *       11 ms  10.168.128.1
  3    14 ms    13 ms    14 ms  212.179.160.142
  4     *        *        *     Request timed out.
  5     *        *        *     Request timed out.
  6     *        *       47 ms  62.219.189.169
  7    31 ms    27 ms    32 ms  62.219.189.150
  8    15 ms    14 ms    16 ms  192.114.65.202
  9    15 ms    15 ms    11 ms  212.143.10.66
 10    13 ms    29 ms    31 ms  212.143.12.234
 11    35 ms    15 ms    18 ms  212.143.8.72
 12    22 ms    22 ms    16 ms  194.90.1.5

I usually ping 194.90.1.5 (which is not at my ISP) with 15ms response time and no losses.

Things I've done/tried:

  • [2012-03-26] I replaced the cable; I thought that made a difference, but the disconnects were back a while later, so that wasn't it.
  • Updated the NIC driver.
  • Tried reducing the MTU (used a utility called Dr. TCP); there was no effect.
  • I updated my board BIOS revision (which caused all the HW to be
    "reinstalled" or re-identified – successfully).
  • I installed another NIC, and tried switching to it – same effect with the on-board NIC.
  • A while back I tried another router (although it was an Edimax model) – same problem.
  • Connected the computer directly, with no router. Same problem.
  • ping -t to the router (192.168.0.254) gives pongs, nothing is lost, and time
    is < 1 ms almost always (sometimes it says 1 or 2 ms). This is the case also during the disconnects.

Best Answer

You seem to have tried about anything local, as well have proper working DHCP and DNS settings. 192.117.235.235 matches nfdns.bezeqint.net, which appears to be a locally available DNS server not accessible from the outside.

Thus, the only thing left to do is to check up with your ISP, having them look in their logs or monitoring your connection over an extended period; this will help you to divide and conquer the possible locations and come to an eventual conclusion.

By the options you listed it's most likely the connection between the ISP and the modem, or the connection between the modem and the router. The router and everything beyond that have been excluded, except for the acteal motherboard itself as well as certain third-pary hardware that could have an influence; if calling the ISP doesn't resolve the problem you could make an at trying to disconnect as much as possible to see whether that helps.

As long as you try to divide and conquer, excluding things that are verified to not cause the problem allows you eventually get to the cause of the problem. Read more about it on the Super User blog...

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