Hello Xbox Forums,
I've been trying to fix this problem for about a day now. I could no longer connect to Xbox LIVE after I played Need For Speed Underground 2 (Which took 5 reboots of the Xbox to run without freezing:P).
My Xbox claims it's an MTU issue, when on my router page I have tried toggling the MTU to Auto as well as setting it manually over 1364 (Minimum for Xbox LIVE).
Here's some more info:
What Country/State/Province do you live in? British Columbia, Canada
Modem brand & model number: Motorola SURFboard Model:SB5102
Router brand & model number: Linksys WRT160N v3
Network Connection Type: Wired
If Wireless, what type of encryption are you using?N/A
If Wireless, are you using a white or black external adapter, or an internal (Xbox 360S) adapter?N/A
Things you have tried: Every suggestion I have found (Restarting modem and router, changing MTU, simplifying my setup, connecting directly to modem (Which actually makes it worse, more on that later))
Is UPnP Enabled? No, but it doesn't work when enabled either.
Is NAT Type Open? Yep
Any Error Codes you encounter: No error codes I can find, just complaints that the MTU is insufficient
W: 0000 - 000B
X: 0000 - F001
Y: 0000 - 0000
Z: 0000 - 0000
ID: 0003 - 0001
What type of internet do you have? Cable/DSL/T1/3G? DSL
Who is your ISP(Internet Service Provider)? Shaw Communications
After you run "Test Xbox LIVE connection" and click on "More info", what is the exact message shown on screen? Your network doesn't have a sufficient MTU setting. Xbox LIVE requires a minimum MTU setting of 1364. On your PC, go to your router configuration webpage and set the MTU to auto, 1364 or higher. If that doesn't work, disconnect your console from the router and connect directly to the modem.
I have changed my MTU, nothing different happens. Funny enough, when I connect directly to the modem, the Xbox doesn't connect because it can't obtain an IP address.
This all happened after I downloaded and ran the compatibility pack for NFSU2, so I tried finding that pack and deleting it, but could not find it.
Just to be clear, my internet is working FINE, the router is working completely fine (Wireless is working as well as all ethernet ports connected to other computers).
I know my way around a computer very well, and I am quite literate with using the router's settings webpage (I've opened my own NAT numerous times). This has stumped me, and my friends have suggested a LOT of different solutions, none of which have worked. I know where the problem lies, between my Xbox and my router, I just don't know how to fix it, and at this point I'm tired and irritated and just want to play some AC Brotherhood online, CMON GUYS HELP ME FIX THIS :)