Hi. If like me you've been suffering from the "The connection with one or more player has been lost" message, follow this. It worked for me and lots of others too. I'm no whizz kid or anything. I just know it works. I now have no problem connecting to the Multiplayer option first time, every time.
I wrote this description on my blog to explain everything step by step.
I hope it helps some of you out.
Cheers.