What is an MTU and why is it important?

MTU problems while trying to connect to Xbox Live?

• Hi and thank you for responding! I am living in a school's residence with it's own internet network, so I just have to plug a ethernet cable in the wall to get high speed internet on my computer. But this doesn't work with my Xbox 360. When I try to connect, I get an error after getting on the network. It says that my MTU is too low. I've bought a router and tried to get on live. Now, I can get on the internet, but it fails while getting on live. It still talk about too low MTU. I've tried to change to MTU of my router, but it was already at 1500. So, I guess it's all about the school connection who have a too low MTU. But is there something i can do about it? Thanks a lot for answering me!

• Answer:

  I had this trouble with my ISP (DODO) Changed ISP and now its fine. Basically your modem is at 1500 or 1492 as a max, but your network cards may not be at 1500 MTU hence there is a slow point somewhere. They probably set it like that so you can't game online. If your ping is too low due to a lower MTU ur connection will be unstable and keep disconnecting. Contact the ITD Dept of the School perhaps they will help.