Expect Uncharted 4 Beta Problems
If you aren't built to deal with bugs and problems, don't try the Uncharted 4 multiplayer beta. It's as simple as that.
While we are getting close to the public Uncharted 4 release date, this is still an early piece of software. A very complex piece of software with tons of moving parts.
There are going to be problems. How many, we can't say, but you should expect to encounter bugs, server problems and performance issues during your trial run with the game.
The point of a beta is to weed out these issues ahead of the public release and you'll want to report as many o these issues as you can so that the developer can go to the drawing board and get them handled before March arrives.