Hey guys,
I've just tried setting this up and at first couldn't get it working, but I found out why.
There are two Exe files that start the game, make sure that the target is using the nwmain.exe and not nwn.exe.
nwn.exe is just a wrapper for the nwmain, as in... it starts with a launch menu where you can select a few options, before you hit "Play game" and actually start nwmain.exe
so your target should be:
C:\NeverwinterNights\NWN\nwmain.exe +connect 84.238.20.74:5121
Not:
C:\NeverwinterNights\NWN\nwn.exe +connect 84.238.20.74:5121