Out of curiosity, where are you located in the world?
Battlefront does some process in the background where it pings servers, and only allows you to join games running on servers that it deems acceptable.
If your internet latency (ping) is too high, or you are in a remote location far away from a server, you won't be able to play very well.
I'm in south africa and during quiet days I can't join any games either.
No port forwarding should be required (Port forwarding is for inbound connections, you don't have to port forward based on the inherent nature of dedicated servers and how you connect to them.)
UNLESS: Your ISP or network manager is blocking your OUTBOUND game communication.
Please visit www.speedtest.net and allow it to run a speedtest to your closest server and post back the result.
Stats from http://swbstats.com/