Due to Gunz going back to the Igunz way of doing things, you will now notice that you AE a lot more during quests, DM's, TDM's, CW's, etc. There is no REAL way to avoid this, it seems to affect those on routers more then anyone else. The best way to avoid this is to relog every time you exit a Quest or Clan War. TDM's / DM's I haven't personally had this problem but try it.

Also, if you ALT+TAB in a game room, you need to relog, otherwise you will Agent Error to everybody.

To fix the glitched AE's (not the AE's due to not forwarding ports whether it's you not forwarding or the other person)
1) Make a game.
2) Start the game.
3) Quit the game.
4) Tis all good.

If you're doing this for CWing, then make sure you do it before ever CW.