I don’t think TFS cares about the packet type, just that it’s the first packet sent by the client. However, you’re missing a lot of information in your login packet (client data, XTEA key, RSA encryption, etc.): forgottenserver/src/protocollogin.cpp at 31d6e85de2a86fb3f0e36c63509fba75b855b8bd ·...