It's to be expected that if you're playing a Battlefield title at launch, you are more than likely going to encounter technical issues. Battlefield 4 is no exception, with a number of problems reported for both PC and console versions of the game. Server crashes are among the most annoying -- any progress you've made for unlocks in that round are lost. Talk about aggravating.
Keep an eye on this forum thread for known issues, if you're having any problems. DICE says that as of today, it's rolled out a server update for all platforms that fixes the most common type of server crash. It sounds as if there are multiple types of crashes/freezes being encountered, however, so there's plenty more progress to be made. Par for the course, sadly.