Well, according to the current char_athena.conf file and so on, it states:
// Set this to what your server's public IP address is.
//char_ip: 127.0.0.1 So if you follow the instructions, i guess you shouldn't have any issues at all. It's just that (as stated above) i've had issues in the past with the ip conf settings, which forced me to set the login ip address as well in the login_athena.conf for instance. (there were other weird issues as well, but bare with me, i don't have the best brain to save memories from what happened a week ago and this goes 10 years back) So on my rA SVN rev. 13742 and older (back to eAthena) it worked with the local IP address set
And when i updated to the latest revision (which was quite a big update) global address ip was required and caused my initial issue stated at the very top.