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).

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.