FRITZ!Box 7390 telephone disconnects

Fritz!box 7390Last year I got a fiber connection to my home (FTTH), and now I have internet and my phone running over this, using a FRITZ!Box 7390 modem/router. Everything works fine and the FRITZ is a very nice modem/router. However, when making long(er) telephone calls (typically over 10 minutes) my wife (I don’t phone that long;) experiences random disconnects. So, last night I had a look at this problem. Seems like more people experience this, and I also found a entry describing the problem at It says a.o. that the problem would be resolved in the upcoming firmware upgrade. Now I was behind with my FW upgrades, so I decided to upgrade my FRITZ to FRITZ!OS 05.51, Firmware version: 84.05.51. First signs are promising. My wife did a 30+ minute telephone call, with no disconnects;)

Edit: Second test, this evening (may 29th) my wife phoned for over 1h15m, again with no disconnects. I’d say, mission success.

— Max

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 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
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 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
link3: (tip!)

— Max