When I try to join a BF4 server I lose connection after 10 seconds with the message "ERROR Game disconnected: client closed down connection."
i have the same problem and i had a similar problem with battlefield 3 where it said game disconnected: could not join server
I FOUND A FIX FIX FIX FIX FIX................... I hope it works for u!
1st-(go to your router webpage)
find the UPnP option, enable it
(also plz check start menu-->service's--> click extended tab,--> find SSDP (right click it) set it to AUTO make sure its STARTED/RUNNING! then do the same for UPnP service under the extended tab)
and your "CLIENT CLOSED DOWN CONNECTION" problem should be fixed!
plz post back if this works for you!!
on another note if your running crossfire(multiple graphic cards) you may have to turn off crossfire and run a single card until full version is released, or crossfire is patched so multiple cards will work I was getting 14fps with crossfire turned on.... after I turned this off and just ran 1 card I never dropped below 40fps @ 1920x1080 on ultra. I cant wait for them to get crossfire working!!!!!
good luck and please post if this solves your problem ...