What do these xbox 360 error reports mean?

I have been trying to connect to xbox live since Christmas and with no luck. Every time I try and connect it always says I have to change my MTU setting as I am below minimum. But I'm not I'm over, and these error codes always show up. W: 0000-000B X: 0001-8005 Y: 0000-0000. Z: 0000-0000 ID: 0003-0001. I have already got in touch with Microsoft and my Internet service provider and they both have no clue why it won't connect.