Error 101 (net::ERR_CONNECTION_RESET): The connection was reset

This evening I solved a problem which was bothering me for 6(!) months. What was the matter? The matter was that a site I used to visit suddenly became unreachable last december 2011. Chrome gave me:

“Error 101 (net::ERR_CONNECTION_RESET): The connection was reset.”

And Firefox and IE9 didn’t work either. The weird thing was, all other sites worked perfectly well, just this one site was unreachable. It became stranger when I discovered that the site worked fine if I went through a proxy. Also from another PC (behind the same router and switch) the site was working fine. So, what could it be?

It couldn’t be the router (see above, the other PC worked)
It couldn’t be some antivirus program (I don’t have any)
It couldn’t be a firewall (I don’t have any)
It couldn’t be the browser (as all browsers had the same trouble)

It had to be something buried deep inside my Windows 7 Home Premium SP1 setup

I googled, man did I google, and I followed myriad of tips, hints and tricks, to no avail. But I’m no guy to give up that easily so last few days I felt the urge to give the problem another try. I felt the solution was near. I stumbled on info on the netsh command, digging deeper, getting close.

And then I found a guy (jobeard) talking about the MTU here http://www.techspot.com/community/topics/error-101-if-anybody-could-help-it-would-be-much-appreciated. Good old MTU. I did know of this MTU from old times (the WIN98 times:) Could it be this MTU setting rearing it ugly head? Why not. So I followed his advice to try the following commands:

ping -f -l nnn domain.name
where nnn is the MTU to be tested. Keep reducing it by 32 until ping runs.
Use that MTU on the router or via Regedit on that system

And I discovered that MTU=1504 (my current setting) didn’t work and MTU=1472 did work!

So, he said to put that MTU setting … but where and how? Google is your friend and the following page was quickly found http://www.mydigitallife.info/how-to-set-and-change-mtu-in-windows-7-or-vista where it was explained that I should enter the following netsh command:

netsh interface ipv4 set subinterface “Local Area Connection” mtu=1472 store=persistent

And with that command my troubles were gone. The unreachable site was reachable again! Problem solved after 6(!) months. As always, when you find the solution it seems so simple. MTU … sure, what else? But to get there I did visit many a webpage with legions of people having the same kind of troubles and other legions handing out tips and tricks like there was no tomorrow. But sure, among those hordes there was this one guy who DID give the golden tip. Jobeard … Thx man:)

problem: Error 101 (net::ERR_CONNECTION_RESET): The connection was reset (Chrome, but other browsers as well)
platform: Windows 7
solution: Set the proper MTU value
link1: http://www.techspot.com/community/topics/error-101-if-anybody-could-help-it-would-be-much-appreciated
link2: http://www.mydigitallife.info/how-to-set-and-change-mtu-in-windows-7-or-vista
link3: http://www.richard-slater.co.uk/archives/2009/10/23/change-your-mtu-under-vista-or-windows-7/ (tip!)

– Max

18 thoughts on “Error 101 (net::ERR_CONNECTION_RESET): The connection was reset

  1. i have the same error, but when i write
    ping -f -l 1472 ‘website’ it says:
    pinging with 1472 bytes of data
    request timed out
    request timed out
    request timed out ….
    help ?

  2. Lowered it by 2 each time, twice it worked, twice the page failed to load, tested it a second time after each failed attempt and it was telling me it couldn’t respond again….

  3. 1472 is the ping buffer size. The actual number of bytes carried by the L2 frame would be 1472 plus 28 bytes (IP and ICMP header). Did you try to set the MTU to 1500?

    I also have it set by default to 1504 and never had to change but I don’t understand why it’s not set to 1500 which is the standard for LANs

  4. For me neither, it did not work… I cannot access my local Synology web server… The Administration Tool : DSM 4.1 is accessible on port 5000, but on the port 80 index.php give the connexion reset error, and this always, not only once or sometime… Always…

  5. Pingback: Fibertel me esta bloqueando un dominio?? tusfiles.net

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