My NAT is Moderate, wich ports needs to be opened to change it?

Moderate is fine, I had no problem playing MP and mine said the same, Until recently where my connection just drops for no reason.

Mine is too but I rarely get disconnected. Are you having connection problems?

Here are the ports from the readme.txt

Game Port Usage

For all traffic between server and client 'game' port is used
(default 64100 - net_lobby_gamespy_online_port).

Ports
SDK Service Hostname Type Local Remote

Available hbmaster3 crysis2.available.gamespy.com UDP Any 27900
NN natserver1 natneg1.gamespy.com UDP game 27901
NN natserver2 natneg2.gamespy.com UDP game 27901
NN nat neg Game client UDP game game*(other game)
QR2 hbmaster3 crysis2.master.gamespy.com UDP game 27900
QR2 Incoming queries Game client UDP game Any
CDKey keymaster key.gamespy.com UDP game 29910
SAKE Profile settings/stats crysis2.sake.gamespy.com TCP Any Any (def:80)
Chat Any IRC server peerchat.gamespy.com TCP Any 6667
GP gpmanager gpcm.gamespy.com TCP Any 29900
GP searchmanager gpsp.gamespy.com TCP Any 29901
SB gmaster3 crysis2.ms5.gamespy.com TCP Any 28910
SB Server queries game servers UDP Any game*(target server)
RSS RSS Feed lb.crysis2.ea.com TCP 80 80

Default value for 'game' is 64100 (can be adjusted).
For incoming UDP traffic, only port "game" ( default 64100)
is required to be opened.

They also listed all the ports the games uses in the Manual, they could not have made it easier

NAT here is moderate too..And I get disconnected ALLLLL the freakin time.
I am extremely lucky if i get to finish a round.

I have a moderate as well,no problem at all low ping as well. think you dont need to change anything.it depends how fast you have an internet connection I have 8Mb.or probz its your router,I had O2 router was crap but I bought a netgear one so its better now.check your firewall and antivirus coz somtimes they cause some problems I have free avast and free zonealarm no problem. I had avira antivirus before but it was crap