Trouble connecting to multiplayer sessions on in's Creed Brotherhood?

It may be your router's NAT type. If it is set to closed or moderate, then you will have problems playing with other people online. I'm sorry if this is not the case, as I do not know what your router setting is. An easy way of finding out is by going into the multiplayer menu of most COD games, as it will tel you there, If it is closed or moderate, then google how to change your NAT type :)