Like I already said.
1. Make your data folder into a grf file.
2. List the grf in the data.ini.
3. Give the grf + exe + data.ini to your brother
4. Profit!?
And ofc he can´t connect with the 2011 client. Because that client normally can´t read the data folder.
And if the client can´t read the data folder, it won´t be able to read the clientinfo aswell. Thus he won´t even reach your server.
My real concern currently is how you can connect to your server if you don´t have a grf and use that client...