Open Question: how can i change nat type for mobile broadband?

my cod wont find any games at all on strict only on moderate and it some how is changing between the two types every week or so?? and i need to now how to change it! im using 3 mobile broadband and theres no help on the website (of course wen do you ever find the answer on the companys website?) and none of the solutions ive typed into google work so far? any solutions??