are you using minilogin or EQEmuLoginServer? this sounds like a config problem of server files 5998 SoF and older clients, 5999 SoD and newer clients. if you are using minilogin client change the Login opcodes in opcode.conf file
Code:
#Login opcodes
OP_SessionReady=0x0001
OP_Login=0x0002
OP_ServerListRequest=0x0004
OP_PlayEverquestRequest=0x000d
OP_PlayEverquestResponse=0x0021
OP_ChatMessage=0x0016
OP_LoginAccepted=0x0017
OP_ServerListResponse=0x0018
OP_Poll=0x0029
OP_EnterChat=0x000f
OP_PollResponse=0x0011