Can't load website; wants a max MTU/MRU of 302 bytes?

splice — Tue, 13 Jan 2009 09:35:52 -0800

Since this weekend I have been unable to access a website. I am network tech so troubleshooting problems like this is my thing, but this one has me stumped. Come in if you know TCP/IP and Path MTU Discovery! This weekend a website stopped loading for me. The website itself doesn't matter (www.dailymotion.com). The strange thing is that it loads fine through a proxy, or from work. So I set about investigating.

That is the only site so far I have found which does not respond. It worked fine before the weekend. Firefox will connect to the site, but hang indefinitely waiting for a reply.

I can ping the site fine. I can traceroute to it. I can telnet to port 80 and get a connection, but no reply to my requests. If I sniff a connection in progress, I will see the standard SYN, ACK, SYN/ACK, the GET request, and then TCP lost packets and DUP ACKs.

I am over PPPOE. I recalled that there may be issues with MTUs and all that jazz. I used ping to try and determine when I get fragmentation and when I get no reply. My packets are fragmented over 1464 bytes (my MTU is 1492) but I get no reply below that size anyway. I only get a reply for packets which are 274 bytes or smaller (not including the header).

This seems to indicate that there is a link somewhere that will not pass packets bigger than 302 bytes total. This makes very little sense to me. The minimum MTU is supposed to be 576.

What could be going on? How could I go about fixing it? This is confusing me.... Any help is appreciated!

Xbox 360 won't connect, thus limiting my 'rocking out' time.

cgomez — Sat, 19 Jul 2008 15:27:03 -0800

I've been using my Xbox 360 for almost a year without any networking problems. As of two days ago, it will not log into Xbox Live and the problem has gotten worse. I've been using the Xbox 360 on my network with an Apple AirPort Extreme (802.11n) and a cable internet connection without issue. On Thursday, I tried to get online and it wouldn't sign in - the network test failed on the MTU stage. I didn't have time to troubleshoot it then, so I waited until this morning. Now that I've been working with it, I tried swapping ethernet cables, power it off, along with my router and cable modem and such, now it won't even get an IP address. I even went so far as plug the 360 directly into the modem and restart the modem.

Is there a way to reset the 360 completely (and not lose my profile, downloaded content)? I'm certain that there is something on the 360 that is causing the problem. I've reset the 360 network settings to default, but they weren't change in the first place.

This is quite frustrating, please help. All logical attempts at remedying this have failed.

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Can't load website; wants a max MTU/MRU of 302 bytes?

Xbox 360 won't connect, thus limiting my 'rocking out' time.