first of all go to your system folder and make a txt file and inside put l2.exe -L2ProtocolVersion and you get number of protocol version,ok now go to config of your loginserver, my path is C:\server [CT3]\L2Server\config\network\GameServer.ini and search for it.
# Numbers of protocol revisions that server allows to connect.
# Delimiter is ;
# WARNING: <u><b><font color="red">Changing the protocol revision may result in incompatible communication and many errors in game!</font></b></u>
# Default: 389;392;393
AllowedProtocolRevisions = 389;392;393;396;398
there add your protocol revision and try login now.