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
Encounters with Reality 
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 ?
Some sites do not allow to be pinged, perhaps your website is one of those.
for mtu check
http://www.mydigitallife.info/how-to-set-and-change-mtu-in-windows-7-or-vista/
http://www.richard-slater.co.uk/archives/2009/10/23/change-your-mtu-under-vista-or-windows-7/
see if your mtu is ‘high’ and if you really think it is the problem, just lower it, and see if it comes up again. Make mtu 1472 or even 1440.
— Max
Thanks so much!
Having the same issue but can’t find a fix for MAC OSX!
wow thanks man ^^
will try this out now. have the exact same problem. hopefully it works. thanks so much
Thank you very much!
entire process was successful, however the problem still remains the same :(
pls help.
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….
32*
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
MTU is a multiple of 8 bytes to a max of 1500
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…
Thanks a million Max..it worked for me with mtu=1436
Thanks so much from NYC!
dowenlood
Thanks a lot.
Wow — absolutely what I needed! Thanks for saving me from pulling out any more hair!
Cheers:)
Great – I was looking for weeks to find a solution ! Thanks !!!
No problem. Glad it helped:)
So I’m a little confused. Exactly where do I get that command prompt box to show up and once I have it up what do I do.
Hi, if you don’t know how to the command box, I guess/fear this problem is a little over your head … but of course you can try/learn. The command box opens up by going to the RUN option in your start menu and then type CMD … and press ENTER. From there on it only starts to be more ‘tech head’ because you enter in the world of the ol’ command line options (no mouse to help you there;)
Hello Max.
I was exactly in the same case, removing firewalls or antiviruses was useless, resetting some parameters too.
Then i tried your solution, and it still not working ! Sometimes i ping with an MTU (1404), and if i do a second ping with the same MTU, it does not work, so nvm i set the MTU of my network card to 1404, and nothing special happen…
Help :(
I’m not sure my solution is always the correct one. In my case it worked (for this 1 site I was trying to reach). And of course, once the problem was gone I stopped with figuring out what exactly was causing the problem. To me it seemed to be this MTU setting, although I’m hesitant to say that it always is the correct solution. E.g. I have read that it also could be provider related (so, in that case you should contact your provider). Anyway, I can’t offer you more help. Good luck.
0MG THAT IS FANTASTIC BUT I DON’T KNOPW WHAT IS MTU PLEAS HELP.
MTU is the maximum transmission unit. Default is 1500. Some systems add overhead when receiving MTU packets, so by doing this, you set your MTU lower and the overhead on the other end does not exceed the 1500 MTU size preventing the packets from dropping.
What worked for me was to go to the site through my search engine. This link opened ok so I figured perhaps the site URL had changed. Sure enough when I updated my bookmarks entry and my desktop shortcut icon both now open the site immediately.
Thank you soooooo much ive been putting up with this and using my iphone for a few months now!! Been googling for days and none of the fixes worked. Thanks to this GEM i can access mail on PC again and download file attachments:) love you
needed to reduce it from 1500 to 1464.
Cheers:)
2012 and up – Issue: Cannot access NuGet repositories. Cannot access Bing.Com. Cannot access MSN.Com. Certain websites do not load properly such as TMobile.com
Cause – The TCP ECNCapability protocol is causing Windstream to drop the packets. Windstream will neither fix nor acknowledge the issue.
Fix: From an elevated command prompt, type the following command and hit enter. Bing.Com should immediately begin working.
netsh int tcp set global ecncapability=disabled
Dude, after 5 years or so, this solutions is still viable, thank you so much, it was driving me insane