@jimp:
I'm saying you can do just IPsec for client access, you can do just L2TP for different clients to access, but you can't do IPsec+L2TP together for client access.
L2TP on its own provides no encryption, it's just a tunneling protocol. If something connects with purely L2TP, it would work fine, just doesn't get encrypted. That's why people want L2TP+IPsec, IPsec handles the encryption (in transport mode), and L2TP handles the tunneling of client data.
So if you have, say, an iPhone connecting with IPsec, and an Android phone connecting separately to L2TP, they could both connect and work. You just really wouldn't want to do that since the L2TP client would have no encryption.
Oh, I see. Thank you for your reply.