Renewal:

SERVER SIDE:

Please, edit the mmo.h file:

For rathena:
https://github.com/rathena/rathena/blob/master/src/common/mmo.h

For hercules:
https://github.com/HerculesWS/Hercules/blob/master/src/common/mmo.h

and edit the #define PACKETVER to 20130807

Example:

#define PACKETVER 20130807

Save the file, then you need to compile your emulator again.

CLIENT SIDE:

You just need to edit the clientinfo.xml which is located in the GRF called ragnarok.grf

1. Download the GRF editor from here: https://rathena.org/board/files/file/2766-grf-editor/
2. Install the program and launch it.
3. Extract the file called clientinfo.xml
4. Edit the IP address 127.0.0.1 to the IP's server address and then save the file.
5. Update your GRF ragnarok.grf with the new clientinfo.xml.