[pabscars]

I dont know about your modem (try posting its type and make etc) but on mine there is no facility to change the MTU value,

It might be beneficial to reset everything back to standard, if youve been messing with it, as long as you know what your doing, but i would be tempted to write down all the important info on a piece of paper should you need to input that info later.

One thing i forgot to ask, have you changed or altered anything recently on your setup, that maybe affecting or causing your problem.

Re: your modem, ive read and found out for myself, that whenever you plug a new piece of kit into your modem via ethernet, you must reboot the modem first, as the modem is only capable of one output at a time (that then normally goes to a router) and is then distributed to your network for eg xbox, pc, laptop etc.

So when you unplug your router to plug your console in direct, the modem still thinks its connected to the router, and wont connect to the console. Unless you reboot the modem first, then switch on your console and it should then connect to live.

If you then want to connect your router back again, then power down the modem and router, switch the modem on, wait for the lights to settle down, then switch on the router, wait for them to settle, then your console, pc, laptop etc may be switched on.

I,m no expert by the way, so cant give you much more info, have you tried another console or taken yours to a friends to try it on there network.